Expression and use of novel pesticidal toxins

ABSTRACT

A novel pesticidal toxin isolated from  Bacillus thuringiensis  that is highly active against a wide range of lepidopteran insect pests is disclosed. The DNA encoding the pesticidal toxin can be used to transform various prokaryotic and eukaryotic organisms to express the pesticidal toxin. These recombinant organisms can be used to control lepidopteran insects in various environments.

The present application is a 371 of PCT/US02/10264, filed Apr. 1, 2002,which claims the benefit of U.S. Provisional Application Ser. No.60/280,025, filed Mar. 30, 2001 and the benefit of U.S. ProvisionalApplication 60/336,657, filed Dec. 4, 2001.

FIELD OF THE INVENTION

The present invention relates to novel Vip3 toxins from Bacillusthuringiensis, nucleic acid sequences whose expression results in saidtoxins, and methods of making and methods of using the toxins andcorresponding nucleic acid sequences to control insects.

BACKGROUND

Plant pests are a major factor in the loss of the world's importantagricultural crops. About $8 billion are lost every year in the U.S.alone due to infestations of non-mammalian pests including insects. Inaddition to losses in field crops, insect pests are also a burden tovegetable and fruit growers, to producers of ornamental flowers, and tohome gardeners.

Insect pests are mainly controlled by intensive applications of chemicalpesticides, which are active through inhibition of insect growth,prevention of insect feeding or reproduction, or cause death. Goodinsect control can thus be reached, but these chemicals can sometimesalso affect other, beneficial insects. Another problem resulting fromthe wide use of chemical pesticides is the appearance of resistantinsect varieties. This has been partially alleviated by variousresistance management practices, but there is an increasing need foralternative pest control agents. Biological pest control agents, such asBacillus thuringiensis strains expressing pesticidal toxins likeδ-endotoxins, have also been applied to crop plants with satisfactoryresults, offering an alternative or compliment to chemical pesticides.The genes coding for some of these δ-endotoxins have been isolated andtheir expression in heterologous hosts have been shown to provideanother tool for the control of economically important insect pests. Inparticular, the expression of insecticidal toxins in transgenic plants,such as Bacillus thuringiensis δ-endotoxins, has provided efficientprotection against selected insect pests, and transgenic plantsexpressing such toxins have been commercialized, allowing farmers toreduce applications of chemical insect control agents.

Other, non-endotoxin genes and the proteins they encode have now beenidentified. U.S. Pat. Nos. 5,877,012, 6,107,279, 6,137,033, and6,291,156, as well as Estruch et al. (1996, Proc. Natl. Acad. Sci.93:5389-5394) and Yu et al. (1997, Appl. Environ. Microbiol.63:532-536), all herein incorporated by reference, describe a new classof insecticidal proteins called Vip3. Vip3 coding sequences encodeapproximately 88 kDa proteins that are produced and secreted by Bacillusduring its vegetative stages of growth (vegetative insecticidalproteins, VIP). The Vip3A protein possesses insecticidal activityagainst a wide spectrum of lepidopteran pests, including, but notlimited to, black cutworm (BCW, Agrotis ipsilon), fall armyworm (FAW,Spodoptera frugiperda), tobacco budworm (TBW, Heliothis virescens), andcorn earworm (CEW, Helicoverpa zea). More recently, plants expressingthe Vip3A protein have been found to be resistant to feeding damagecaused by hemipteran insect pests. Thus, the Vip3A protein displays aunique spectrum of insecticidal activities. Other disclosures, WO98/18932, WO 98/33991, WO 98/00546, and WO 99/57282, have also nowidentified homologues of the Vip3 class of proteins.

The continued use of chemical and biological control methods heightensthe chance for insects to develop resistance to such control measures.Also, only a few specific insect pests are controllable with currentmeasures.

Therefore, there remains a need to discover new and effective pestcontrol agents that provide an economic benefit to farmers and that areenvironmentally acceptable. Particularly needed are control agents thatare targeted to a wider spectrum of economically important insect pestsand that efficiently control insect strains that are or could becomeresistant to existing insect control agents. Furthermore, agents whoseapplication minimizes the burden on the environment are desirable.

SUMMARY

The present invention addresses the need for novel pest control agentsby providing new genes and toxins that are distinct from those disclosedin U.S. Pat. Nos. 5,877,012, 6,107,279, and 6,137,033, and Estruch etal. (1996), and Yu et al. (1997), as well as WO 98/18932, WO 99/33991,WO 99/5782, and WO 98/00546.

Within the present invention, compositions and methods for controllingplant pests are provided. In particular, novel vip3 nucleic acidsequences isolated from Bacillus thuringiensis, and sequencessubstantially identical thereto, whose expression results in pesticidaltoxins with high specific toxicity to economically important insectpests, particularly insect pests that infest plants, are provided. Theinvention is further drawn to the novel pesticidal toxins resulting fromthe expression of the nucleic acid sequences, and to compositions andformulations containing the pesticidal toxins, which are capable ofinhibiting the ability of insect pests to survive, grow and reproduce,or of limiting insect-related damage or loss to crop plants. Theinvention is also drawn to methods of using the nucleic acid sequences,for example in making hybrid toxins with enhanced pesticidal activity orin a recombinogenic procedure such as DNA shuffling. The invention isfurther drawn to a method of making the toxins and to methods of usingthe nucleic acid sequences, for example in microorganisms to controlinsects or in transgenic plants to confer protection from insect damage,and to a method of using the pesticidal toxins, and compositions andformulations comprising the pesticidal toxins, for example applying thepesticidal toxins or compositions or formulations to insect-infestedareas, or to prophylactically treat insect-susceptible areas or plantsto confer protection against the insect pests.

The novel pesticidal toxins described herein are highly active againstinsects. For example, a number of economically important insect pests,such as the lepidopterans Ostrinia nubilalis (European corn borer),Plutella xylostella (diamondback moth), Spodoptera frugiperda (fallarmyworm), Agrotis ipsilon (black cutworm), Helicoverpa zea (cornearworm), Heliothis virescens (tobacco budworm), Spodoptera exigua (beetarmyworm), Diatraea grandiosella (southwestern corn borer), Diatraeasaccharalis (sugarcane borer), Sesamia nonagroides (mediterranean cornborer), Helicoverpa punctigera (native budworm) and Helicoverpa armigera(cotton bollworm) can be controlled by the pesticidal toxins. Thepesticidal toxins can be used singly or in combination with other insectcontrol strategies to confer maximal pest control efficiency withminimal environmental impact.

According to one aspect, the present invention provides an isolatednucleic acid molecule comprising a nucleotide sequence that encodes atoxin that is active against insects, wherein the nucleotide sequence:(a) has at least 92% sequence identity with SEQ ID NO: 1; or (b) isisocoding with the nucleotide sequence of (a); or (c) encodes an aminoacid sequence that has at least 91% sequence identity with SEQ ID NO: 3.

In one embodiment of this aspect, the isolated nucleic acid moleculecomprises a nucleotide sequence that has at least 92% sequence identitywith SEQ ID NO: 1.

In another embodiment of this aspect, the isolated nucleic acid moleculecomprises a nucleotide sequence that is isocoding with a nucleotidesequence that has at least 92% sequence identity with SEQ ID NO: 1.

In a further embodiment, the isolated nucleic acid molecule comprisesthe nucleotide sequence set forth in SEQ ID NO: 1 or SEQ ID NO: 3.

In another embodiment of this aspect, the isolated nucleic acid moleculecomprises a nucleotide sequence that encodes an amino acid sequence withat least 91% sequence identity with SEQ ID NO: 2. In a furtherembodiment, the isolated nucleic acid molecule comprises a nucleotidesequence that encodes the amino acid sequence set forth in SEQ ID NO: 3.

In one embodiment, the isolated nucleic acid molecule comprises theapproximately 2.4 kb DNA fragment comprised in pNOV1325 harbored in E.coli strain DH5α, designated as ATCC PTA-3868. In another embodiment,the isolated nucleic acid molecule comprises the approximately 2.4 kbDNA fragment comprised in pNOV1328 harbored in E. coli DH5α, designatedas ATCC PTA-3869.

According to one embodiment of the invention, the isolated nucleic acidmolecule encodes a toxin that is active against a lepidopteran insect.In a further embodiment, the lepidopteran insect is selected from thegroup consisting of Ostrinia nubilalis (European corn borer), Plutellaxylostella (diamondback moth), Spodoptera frugiperda (fall armyworm),Agrotis ipsilon (black cutworm), Helicoverpa zea (corn earworm),Heliothis virescens (tobacco budworm), Spodoptera exigua (beetarmyworm), Helicoverpa punctigera (native budworm), Helicoverpa armigera(cotton bollworm), Manduca sexta (tobacco hornworm), Trichoplusia ni(cabbage looper), Pectinophora gossypiella (pink bollworm), and Cochylishospes (banded sunflower moth).

The present invention also provides a chimeric gene comprising aheterologous promoter sequence operatively linked to the nucleic acidmolecule of the invention. Further, the present invention provides arecombinant vector comprising such a chimeric gene. The presentinvention also provides a virus comprising such a chimeric gene. A virusaccording to this aspect of the invention may be an animal virus or aplant virus. Still further, the present invention provides a transgenichost cell comprising such a chimeric gene. A transgenic host cellaccording to this aspect of the invention may be an animal cell, abacterial cell, a yeast cell or a plant cell, preferably, a plant cell.Even further, the present invention provides a transgenic plantcomprising such a plant cell. A transgenic plant according to thisaspect of the invention may be sorghum, wheat, sunflower, tomato, colecrops, cotton, rice, soybean, sugar beet, sugarcane, tobacco, barley,oilseed rape or maize, preferably maize. Still further, the presentinvention provides seed from the group of transgenic plants consistingof sorghum, wheat, sunflower, tomato, cole crops, cotton, rice, soybean,sugar beet, sugarcane, tobacco, barley, oilseed rape and maize. In afurther embodiment, the seed is from a transgenic maize plant.

Also provided by the present invention are transgenic plants furthercomprising a second nucleic acid sequence or groups of nucleic acidsequences that encode a second pesticidal principle. Particularlypreferred second nucleic acid sequences are those that encode aδ-endotoxin, those that encode another Vegetative Insecticidal Proteintoxin or those that encode a pathway for the production of anon-proteinaceous pesticidal principle.

According to one aspect, the present invention provides an isolatedtoxin that is active against insects, wherein the toxin comprises anamino acid sequence that: (a) has at least 91% sequence identity withSEQ ID NO: 2; or (b) is produced by the expression of a nucleic acidmolecule comprising a nucleotide sequence that has at least 92% sequenceidentity with SEQ ID NO: 1.

In one embodiment of this aspect, the isolated toxin comprises an aminoacid sequence that has at least 91% sequence identity with SEQ ID NO: 2.

In a further embodiment, the isolated toxin comprises the amino acidsequence set forth in SEQ ID NO: 2.

In another embodiment of this aspect, the isolated toxin is produced bythe expression of a nucleic acid molecule comprising a nucleotidesequence that has at least 92% sequence identity with SEQ ID NO: 1.

In yet another embodiment, the isolated toxin is produced by theexpression of a nucleic acid molecule comprising the nucleotide sequenceset forth in SEQ ID NO: 1 or SEQ ID NO: 3.

In another embodiment, the toxins of the invention are active againstlepidopteran insects. In a further embodiment, the toxins are activeagainst Ostrinia nubilalis (European corn borer), Plutella xylostella(diamondback moth), Spodoptera frugiperda (fall armyworm), Agrotisipsilon (black cutworm), Helicoverpa zea (corn earworm), Heliothisvirescens (tobacco budworm), Spodoptera exigua (beet armyworm),Helicoverpa punctigera (native budworm), Helicoverpa armigera (cottonbollworm), Manduca sexta (tobacco hornworm), Trichoplusia ni (cabbagelooper), Pectinophora gossypiella (pink bollworm), and Cochylis hospes(banded sunflower moth).

In a further embodiment, the toxins are produced by the E. coli straindeposited as ATCC accession PTA-3868 or the E. coli strain deposited asATCC accession PTA-3869.

The present invention also provides a composition comprising aneffective insect-controlling amount of a toxin according to theinvention.

In another aspect, the present invention provides a method of producinga toxin that is active against insects, comprising: (a) obtaining atransgenic host cell comprising a chimeric gene, which itself comprisesa heterologous promoter sequence operatively linked to the nucleic acidmolecule of the invention; and (b) expressing the nucleic acid moleculein the transgenic cell, which results in at least one toxin that isactive against insects.

In a further aspect, the present invention provides a method ofproducing an insect-resistant transgenic plant, comprising introducing anucleic acid molecule of the invention into the transgenic plant,wherein the nucleic acid molecule is expressible in the transgenic plantin an effective amount to control insects. According to one embodiment,the insects are lepidopteran insects. In a further embodiment, thelepidopteran insects are selected from the group consisting of Ostrinianubilalis (European corn borer), Plutella xylostella (diamondback moth),Spodoptera frugiperda (fall armyworm), Agrotis ipsilon (black cutworm),Helicoverpa zea (corn earworm), Heliothis virescens (tobacco budworm),Spodoptera exigua (beet armyworm), Helicoverpa punctigera (nativebudworm), Helicoverpa armigera (cotton bollworm), Manduca sexta (tobaccohornworm), Trichoplusia ni (cabbage looper), Pectinophora gossypiella(pink bollworm), and Cochylis hospes (banded sunflower moth).

In a still further aspect, the present invention provides a method ofcontrolling insects comprising delivering to the insects an effectiveamount of a toxin of the present invention. According to one embodiment,the insects are lepidopteran insects. In a further embodiment, thelepidopteran insects are selected from the group consisting of Ostrinianubilalis (European corn borer), Plutella xylostella (diamondback moth),Spodoptera frugiperda (fall armyworm), Agrotis ipsilon (black cutworm),Helicoverpa zea (corn earworm), Heliothis virescens (tobacco budworm),Spodoptera exigua (beet armyworm), Helicoverpa punctigera (nativebudworm), Helicoverpa armigera (cotton bollworm), Manduca sexta (tobaccohornworm), Trichoplusia ni (cabbage looper), Pectinophora gossypiella(pink bollworm), and Cochylis hospes (banded sunflower moth). In anotherembodiment, the toxin is delivered to the insects orally. In a stillfurther embodiment, the toxin is delivered orally through a transgenicplant comprising a nucleic acid sequence that expresses a toxin of thepresent invention.

The present invention also provides hybrid toxins active againstinsects, wherein the hybrid toxins are encoded by a nucleic acidmolecule comprising a nucleotide sequence according to the invention.

In one embodiment, the hybrid toxins of the invention are active againstlepidopteran insects. In a further embodiment, the lepidopteran insectsare selected from the group consisting of Ostrinia nubilalis (Europeancorn borer), Plutella xylostella (diamondback moth), Spodopterafrugiperda (fall armyworm), Agrotis ipsilon (black cutworm), Helicoverpazea (corn earworm), Heliothis virescens (tobacco budworm), Spodopteraexigua (beet armyworm), Helicoverpa punctigera (native budworm),Helicoverpa armigera (cotton bollworm), Manduca sexta (tobaccohornworm), Trichoplusia ni (cabbage looper), Pectinophora gossypiella(pink bollworm), and Cochylis hospes (banded sunflower moth)

In another embodiment, the hybrid toxin is encoded by the nucleotidesequence set forth in SEQ ID NO: 6.

The present invention also provides a composition comprising aninsecticidally effective amount of a hybrid toxin according to theinvention.

In another aspect, the present invention provides a method of producinga hybrid toxin active against insects, comprising: (a) obtaining atransgenic host cell comprising a chimeric gene, which itself comprisesa heterologous promoter sequence operatively linked to the nucleic acidmolecule of the invention; and (b) expressing the nucleic acid moleculein the transgenic cell, which results in at least one hybrid toxin thatis active against insects.

In a further aspect, the present invention provides a method ofproducing an insect-resistant transgenic plant, comprising introducing anucleic acid molecule of the invention into the plant, wherein thenucleic acid molecule encodes a hybrid toxin and wherein the hybridtoxin is expressible in the transgenic plant in an effective amount tocontrol an insect. According to one embodiment, the insects arelepidopteran insects. In another embodiment, the lepidopteran insect isselected from the group consisting of Ostrinia nubilalis (European cornborer), Plutella xylostella (diamondback moth), Spodoptera frugiperda(fall armyworm), Agrotis ipsilon (black cutworm), Helicoverpa zea (cornearworm), Heliothis virescens (tobacco budworm), Spodoptera exigua (beetarmyworm), Pectinophora gossypiella (pink boll worm), Trichoplusia ni(cabbage looper), Cochyles hospes (banded sunflower moth), andHomoeosoma electellum (sunflower head moth).

In a still further aspect, the present invention provides a method ofcontrolling an insect comprising delivering to the insects an effectiveamount of a hybrid toxin of the present invention. According to oneembodiment, the insects are lepidopteran insects. In a furtherembodiment, the lepidopteran insects are selected from the groupconsisting of Ostrinia nubilalis (European corn borer), Plutellaxylostella (diamondback moth), Spodoptera frugiperda (fall armyworm),Agrotis ipsilon (black cutworm), Helicoverpa zea (corn earworm),Heliothis virescens (tobacco budworm), Spodoptera exigua (beetarmyworm), Pectinophora gossypiella (pink boll worm), Trichoplusia ni(cabbage looper), Cochyles hospes (banded sunflower moth), andHomoeosoma electellum (sunflower head moth). In another embodiment, thehybrid toxin is delivered to the insects orally. In a furtherembodiment, the hybrid toxin is delivered orally through a transgenicplant comprising a nucleic acid sequence that expresses a hybrid toxinof the present invention.

The present invention also provides a hybrid toxin active againstinsects, comprising a carboxy-terminal region of a Vip3 toxin joined inthe amino to carboxy direction to an amino-terminal region of adifferent Vip3 toxin, wherein the carboxy-terminal region comprises anamino acid sequence which has at least 75% identity with amino acids579-787 of SEQ ID NO: 2; and wherein the amino-terminal region has atleast 75% identity with amino acids 1-578 of SEQ ID NO: 4. In a furtherembodiment, the carboxy-terminal region comprises amino acids 578-787 ofSEQ ID NO: 2, and the amino-terminal region comprises amino acids 1-579of SEQ ID NO: 5. In a still further embodiment, the hybrid toxincomprises amino acids 1-787 of SEQ ID NO: 7.

The hybrid toxin, according to this aspect of the invention, is activeagainst lepidopteran insects. In a further embodiment, the lepidopteraninsects are selected from the group consisting of Ostrinia nubilalis(European corn borer), Plutella xylostella (diamondback moth),Spodoptera frugiperda (fall armyworm), Agrotis ipsilon (black cutworm),Helicoverpa zea (corn earworm), Heliothis virescens (tobacco budworm),Spodoptera exigua (beet armyworm), Pectinophora gossypiella (pink bollworm), Trichoplusia ni (cabbage looper), Cochyles hospes (bandedsunflower moth), and Homoeosoma electellum (sunflower head moth).

Also encompassed by this aspect of the invention is a nucleic acidmolecule comprising a nucleotide sequence that encodes the hybrid toxinof this aspect.

Also provided by the invention is a method of controlling insectswherein the transgenic plant further comprises a second nucleic acidsequence or groups of nucleic acid sequences that encode a secondpesticidal principle. Particularly preferred second nucleic acidsequences are those that encode a δ-endotoxin, those that encode anotherVegetative Insecticidal Protein toxin or those that encode a pathway forthe production of a non-proteinaceous pesticidal principle.

Yet another aspect of the present invention is the provision of a methodfor mutagenizing a nucleic acid molecule according to the presentinvention, wherein the nucleic acid molecule has been cleaved intopopulations of double-stranded random fragments of a desired size,comprising: (a) adding to the population of double-stranded randomfragments one or more single- or double-stranded oligonucleotides,wherein the oligonucleotides each comprise an area of identity and anarea of heterology to a double-stranded template polynucleotide; (b)denaturing the resultant mixture of double-stranded random fragments andoligonucleotides into single-stranded fragments; (c) incubating theresultant population of single-stranded fragments with polymerase underconditions which result in the annealing of the single-strandedfragments at the areas of identity to form pairs of annealed fragments,the areas of identity being sufficient for one member of the pair toprime replication of the other, thereby forming a mutagenizeddouble-stranded polynucleotide; and (d) repeating the second and thirdsteps for at least two further cycles, wherein the resultant mixture inthe second step of a further cycle includes the mutagenizeddouble-stranded polynucleotide from the third step of the previouscycle, and wherein the further cycle forms a further mutagenizeddouble-stranded polynucleotide.

Other aspects and advantages of the present invention will becomeapparent to those skilled in the art from a study of the followingdescription of the invention and non-limiting examples.

BRIEF DESCRIPTION OF THE SEQUENCES IN THE SEQUENCE LISTING

SEQ ID NO: 1 is the coding sequence of the native vip3B gene.

SEQ ID NO: 2 is the amino acid sequence encoded SEQ ID NO: 1.

SEQ ID NO: 3 is the coding sequence of the maize optimized vip3B gene.

SEQ ID NO: 4 is the coding sequence of the native vip3A gene.

SEQ ID NO: 5 is the amino acid sequence encoded by SEQ ID NO: 4.

SEQ ID NO: 6 is the coding sequence of the hybrid vip3A-B gene.

SEQ ID NO: 7 is the amino acid sequence encoded by SEQ ID NO: 6.

SEQ ID NO: 8-13 are primers useful in the present invention.

DEPOSITS

The following material was deposited with the American Type CultureCollection, 10801 University Blvd., Manassas, Va., under the terms ofthe Budapest Treaty on the International Recognition of the Deposit ofMicroorganisms for the Purposes of Patent Procedure. Access to thedeposits will be available during pendency of the application. Allrestrictions on the availability of the deposited material will beirrevocably removed upon granting of the patent.

Clone Accession Number Date of Deposit pNOV1325 ATCC No. PTA-3868 Nov.16, 2001 pNOV1328 ATCC No. PTA-3869 Nov. 16, 2001

DEFINITIONS

“Activity” of the toxins of the invention is meant that the toxinsfunction as orally active insect control agents, have a toxic effect, orare able to disrupt or deter insect feeding, which may or may not causedeath of the insect. When a toxin of the invention is delivered to theinsect, the result is typically death of the insect, or the insect doesnot feed upon the source that makes the toxin available to the insect.

“Associated with/operatively linked” refer to two nucleic acid sequencesthat are related physically or functionally. For example, a promoter orregulatory DNA sequence is said to be “associated with” a DNA sequencethat codes for an RNA or a protein if the two sequences are operativelylinked, or situated such that the regulator DNA sequence will affect theexpression level of the coding or structural DNA sequence.

A “chimeric gene” is a recombinant nucleic acid sequence in which apromoter or regulatory nucleic acid sequence is operatively linked to,or associated with, a nucleic acid sequence that codes for an mRNA orwhich is expressed as a protein, such that the regulator nucleic acidsequence is able to regulate transcription or expression of theassociated nucleic acid sequence. The regulator nucleic acid sequence ofthe chimeric gene is not normally operatively linked to the associatednucleic acid sequence as found in nature.

A “coding sequence” is a nucleic acid sequence that is transcribed intoRNA such as mRNA, rRNA, tRNA, snRNA, sense RNA or antisense RNA.Preferably the RNA is then translated in an organism to produce aprotein.

To “control” insects means to inhibit, through a toxic effect, theability of insect pests to survive, grow, feed, and/or reproduce, or tolimit insect-related damage or loss in crop plants. To “control” insectsmay or may not mean killing the insects, although it preferably meanskilling the insects.

To “deliver” a toxin means that the toxin comes in contact with aninsect, resulting in toxic effect and control of the insect. The toxincan be delivered in many recognized ways, e.g., orally by ingestion bythe insect or by contact with the insect via transgenic plantexpression, formulated protein composition(s), sprayable proteincomposition(s), a bait matrix, or any other art-recognized toxindelivery system.

“Effective insect-controlling amount” means that concentration of toxinthat inhibits, through a toxic effect, the ability of insects tosurvive, grow, feed and/or reproduce, or to limit insect-related damageor loss in crop plants. “Effective insect-controlling amount” may or maynot mean killing the insects, although it preferably means killing theinsects.

“Expression cassette” as used herein means a nucleic acid sequencecapable of directing expression of a particular nucleotide sequence inan appropriate host cell, comprising a promoter operably linked to thenucleotide sequence of interest which is operably linked to terminationsignals. It also typically comprises sequences required for propertranslation of the nucleotide sequence. The expression cassettecomprising the nucleotide sequence of interest may be chimeric, meaningthat at least one of its components is heterologous with respect to atleast one of its other components. The expression cassette may also beone that is naturally occurring but has been obtained in a recombinantform useful for heterologous expression. Typically, however, theexpression cassette is heterologous with respect to the host, i.e., theparticular nucleic acid sequence of the expression cassette does notoccur naturally in the host cell and must have been introduced into thehost cell or an ancestor of the host cell by a transformation event. Theexpression of the nucleotide sequence in the expression cassette may beunder the control of a constitutive promoter or of an inducible promoterthat initiates transcription only when the host cell is exposed to someparticular external stimulus. In the case of a multicellular organism,such as a plant, the promoter can also be specific to a particulartissue, or organ, or stage of development.

A “gene” is a defined region that is located within a genome and that,besides the aforementioned coding nucleic acid sequence, comprisesother, primarily regulatory, nucleic acid sequences responsible for thecontrol of the expression, that is to say the transcription andtranslation, of the coding portion. A gene may also comprise other 5′and 3′ untranslated sequences and termination sequences. Furtherelements that may be present are, for example, introns.

“Gene of interest” refers to any gene which, when transferred to aplant, confers upon the plant a desired characteristic such asantibiotic resistance, virus resistance, insect resistance, diseaseresistance, or resistance to other pests, herbicide tolerance, improvednutritional value, improved performance in an industrial process oraltered reproductive capability. The “gene of interest” may also be onethat is transferred to plants for the production of commerciallyvaluable enzymes or metabolites in the plant.

A “heterologous” nucleic acid sequence is a nucleic acid sequence notnaturally associated with a host cell into which it is introduced,including non-naturally occurring multiple copies of a naturallyoccurring nucleic acid sequence.

A “homologous” nucleic acid sequence is a nucleic acid sequencenaturally associated with a host cell into which it is introduced.

“Homologous recombination” is the reciprocal exchange of nucleic acidfragments between homologous nucleic acid molecules.

“Hybrid toxin” as used herein is an insecticidal toxin made by the handof man which comprises amino acid regions or fragments of one toxinjoined with amino acid regions or fragments from a different toxin, Forexample, without limitation, joining the C-terminal region of Vip3B,from amino acid number 579 to amino acid number 787 of SEQ ID NO: 2,with the N-terminal region of Vip3A, from amino acid number 1 to aminoacid number 578 of SEQ ID NO: 5.

“Insecticidal” is defined as a toxic biological activity capable ofcontrolling insects, preferably by killing them.

A nucleic acid sequence is “isocoding with” a reference nucleic acidsequence when the nucleic acid sequence encodes a polypeptide having thesame amino acid sequence as the polypeptide encoded by the referencenucleic acid sequence.

An “isolated” nucleic acid molecule or an isolated enzyme is a nucleicacid molecule or enzyme that, by the hand of man, exists apart from itsnative environment and is therefore not a product of nature. An isolatednucleic acid molecule or enzyme may exist in a purified form or mayexist in a non-native environment such as, for example, a recombinanthost cell.

A “nucleic acid molecule” or “nucleic acid sequence” is a linear segmentof single- or double-stranded DNA or RNA that can be isolated from anysource. In the context of the present invention, the nucleic acidmolecule is preferably a segment of DNA.

A “plant” is any plant at any stage of development, particularly a seedplant.

A “plant cell” is a structural and physiological unit of a plant,comprising a protoplast and a cell wall. The plant cell may be in formof an isolated single cell or a cultured cell, or as a part of higherorganized unit such as, for example, plant tissue, a plant organ, or awhole plant.

“Plant cell culture” means cultures of plant units such as, for example,protoplasts, cell culture cells, cells in plant tissues, pollen, pollentubes, ovules, embryo sacs, zygotes and embryos at various stages ofdevelopment.

“Plant material” refers to leaves, stems, roots, flowers or flowerparts, fruits, pollen, egg cells, zygotes, seeds, cuttings, cell ortissue cultures, or any other part or product of a plant.

A “plant organ” is a distinct and visibly structured and differentiatedpart of a plant such as a root, stem, leaf, flower bud, or embryo.

“Plant tissue” as used herein means a group of plant cells organizedinto a structural and functional unit. Any tissue of a plant in plantaor in culture is included. This term includes, but is not limited to,whole plants, plant organs, plant seeds, tissue culture and any groupsof plant cells organized into structural and/or functional units. Theuse of this term in conjunction with, or in the absence of, any specifictype of plant tissue as listed above or otherwise embraced by thisdefinition is not intended to be exclusive of any other type of planttissue.

A “promoter” is an untranslated DNA sequence upstream of the codingregion that contains the binding site for RNA polymerase 11 andinitiates transcription of the DNA. The promoter region may also includeother elements that act as regulators of gene expression.

A “protoplast” is an isolated plant cell without a cell wall or withonly parts of the cell wall.

“Regulatory elements” refer to sequences involved in controlling theexpression of a nucleotide sequence. Regulatory elements comprise apromoter operably linked to the nucleotide sequence of interest andtermination signals. They also typically encompass sequences requiredfor proper translation of the nucleotide sequence.

A “shuffled” nucleic acid is a nucleic acid produced by a shufflingprocedure such as any shuffling procedure set forth herein. Shufflednucleic acids are produced by recombining (physically or virtually) twoor more nucleic acids (or character strings), e.g., in an artificial,and optionally recursive, fashion. Generally, one or more screeningsteps are used in shuffling processes to identify nucleic acids ofinterest; this screening step can be performed before or after anyrecombination step. In some (but not all) shuffling embodiments, it isdesirable to perform multiple rounds of recombination prior to selectionto increase the diversity of the pool to be screened. The overallprocess of recombination and selection are optionally repeatedrecursively. Depending on context, shuffling can refer to an overallprocess of recombination and selection, or, alternately, can simplyrefer to the recombinational portions of the overall process.

Substantially identical: the phrase “substantially identical,” in thecontext of two nucleic acid or protein sequences, refers to two or moresequences or subsequences that have at least 60%, preferably 80%, morepreferably 90, even more preferably 95%, and most preferably at least99% nucleotide or amino acid residue identity, when compared and alignedfor maximum correspondence, as measured using one of the followingsequence comparison algorithms or by visual inspection. Preferably, thesubstantial identity exists over a region of the sequences that is atleast about 50 residues in length, more preferably over a region of atleast about 100 residues, and most preferably the sequences aresubstantially identical over at least about 150 residues. In anespecially preferred embodiment, the sequences are substantiallyidentical over the entire length of the coding regions. Furthermore,substantially identical nucleic acid or protein sequences performsubstantially the same function.

For sequence comparison, typically one sequence acts as a referencesequence to which test sequences are compared. When using a sequencecomparison algorithm, test and reference sequences are input into acomputer, subsequence coordinates are designated if necessary, andsequence algorithm program parameters are designated. The sequencecomparison algorithm then calculates the percent sequence identity forthe test sequence(s) relative to the reference sequence, based on thedesignated program parameters.

Optimal alignment of sequences for comparison can be conducted, e.g., bythe local homology algorithm of Smith & Waterman, Adv. Appl. Math. 2:482 (1981), by the homology alignment algorithm of Needleman & Wunsch,J. Mol. Biol. 48: 443 (1970), by the search for similarity method ofPearson & Lipman, Proc. Nat'l. Acad. Sci. USA 85: 2444 (1988), bycomputerized implementations of these algorithms (GAP, BESTFIT, FASTA,and TFASTA in the Wisconsin Genetics Software Package, Genetics ComputerGroup, 575 Science Dr., Madison, Wis.), or by visual inspection (seegenerally, Ausubel et al., infra).

One example of an algorithm that is suitable for determining percentsequence identity and sequence similarity is the BLAST algorithm, whichis described in Altschul et al., J. Mol. Biol. 215: 403-410 (1990).Software for performing BLAST analyses is publicly available through theNational Center for Biotechnology Information (ncbi.nlm.nih.gov). Thisalgorithm involves first identifying high scoring sequence pairs (HSPs)by identifying short words of length W in the query sequence, whicheither match or satisfy some positive-valued threshold score T whenaligned with a word of the same length in a database sequence. T isreferred to as the neighborhood word score threshold (Altschul et al.,1990). These initial neighborhood word hits act as seeds for initiatingsearches to find longer HSPs containing them. The word hits are thenextended in both directions along each sequence for as far as thecumulative alignment score can be increased. Cumulative scores arecalculated using, for nucleotide sequences, the parameters M (rewardscore for a pair of matching residues; always>0) and N (penalty scorefor mismatching residues; always<0). For amino acid sequences, a scoringmatrix is used to calculate the cumulative score. Extension of the wordhits in each direction are halted when the cumulative alignment scorefalls off by the quantity X from its maximum achieved value, thecumulative score goes to zero or below due to the accumulation of one ormore negative-scoring residue alignments, or the end of either sequenceis reached. The BLAST algorithm parameters W, T, and X determine thesensitivity and speed of the alignment. The BLASTN program (fornucleotide sequences) uses as defaults a wordlength (W) of 11, anexpectation (E) of 10, a cutoff of 100, M=5, N=−4, and a comparison ofboth strands. For amino acid sequences, the BLASTP program uses asdefaults a wordlength (W) of 3, an expectation (E) of 10, and theBLOSUM62 scoring matrix (see Henikoff & Henikoff, Proc. Natl. Acad. Sci.USA 89: 10915 (1989)).

In addition to calculating percent sequence identity, the BLASTalgorithm also performs a statistical analysis of the similarity betweentwo sequences (see, e.g., Karlin & Altschul, Proc. Nat'l. Acad. Sci. USA90: 5873-5787 (1993)). One measure of similarity provided by the BLASTalgorithm is the smallest sum probability (P(N)), which provides anindication of the probability by which a match between two nucleotide oramino acid sequences would occur by chance. For example, a test nucleicacid sequence is considered similar to a reference sequence if thesmallest sum probability in a comparison of the test nucleic acidsequence to the reference nucleic acid sequence is less than about 0.1,more preferably less than about 0.01, and most preferably less thanabout 0.001.

Another indication that two nucleic acid sequences are substantiallyidentical is that the two molecules hybridize to each other understringent conditions. The phrase “hybridizing specifically to” refers tothe binding, duplexing, or hybridizing of a molecule only to aparticular nucleotide sequence under stringent conditions when thatsequence is present in a complex mixture (e.g., total cellular) DNA orRNA. “Bind(s) substantially” refers to complementary hybridizationbetween a probe nucleic acid and a target nucleic acid and embracesminor mismatches that can be accommodated by reducing the stringency ofthe hybridization media to achieve the desired detection of the targetnucleic acid sequence.

“Stringent hybridization conditions” and “stringent hybridization washconditions” in the context of nucleic acid hybridization experimentssuch as Southern and Northern hybridizations are sequence dependent, andare different under different environmental parameters. Longer sequenceshybridize specifically at higher temperatures. An extensive guide to thehybridization of nucleic acids is found in Tijssen (1993) LaboratoryTechniques in Biochemistry and Molecular Biology-Hybridization withNucleic Acid Probes part I chapter 2 “Overview of principles ofhybridization and the strategy of nucleic acid probe assays” Elsevier,N.Y. Generally, highly stringent hybridization and wash conditions areselected to be about 5° C. lower than the thermal melting point (T_(m))for the specific sequence at a defined ionic strength and pH. Typically,under “stringent conditions” a probe will hybridize to its targetsubsequence, but to no other sequences.

The T_(m) is the temperature (under defined ionic strength and pH) atwhich 50% of the target sequence hybridizes to a perfectly matchedprobe. Very stringent conditions are selected to be equal to the T_(m)for a particular probe. An example of stringent hybridization conditionsfor hybridization of complementary nucleic acids which have more than100 complementary residues on a filter in a Southern or northern blot is50% formamide with 1 mg of heparin at 42° C., with the hybridizationbeing carried out overnight. An example of highly stringent washconditions is 0.1 5M NaCl at 72° C. for about 15 minutes. An example ofstringent wash conditions is a 0.2×SSC wash at 65° C. for 15 minutes(see, Sambrook, infra, for a description of SSC buffer). Often, a highstringency wash is preceded by a low stringency wash to removebackground probe signal. An example medium stringency wash for a duplexof, e.g., more than 100 nucleotides, is 1×SSC at 45° C. for 15 minutes.An example low stringency wash for a duplex of, e.g. more than 100nucleotides, is 4-6×SSC at 40° C. for 15 minutes. For short probes(e.g., about 10 to 50 nucleotides), stringent conditions typicallyinvolve salt concentrations of less than about 1.0 M Na ion, typicallyabout 0.01 to 1.0 M Na ion concentration (or other salts) at pH 7.0 to8.3, and the temperature is typically at least about 30° C. Stringentconditions can also be achieved with the addition of destabilizingagents such as formamide. In general, a signal to noise ratio of 2× (orhigher) than that observed for an unrelated probe in the particularhybridization assay indicates detection of a specific hybridization.Nucleic acids that do not hybridize to each other under stringentconditions are still substantially identical if the proteins that theyencode are substantially identical. This occurs, e.g., when a copy of anucleic acid is created using the maximum codon degeneracy permitted bythe genetic code.

The following are examples of sets of hybridization/wash conditions thatmay be used to clone homologous nucleotide sequences that aresubstantially identical to reference nucleotide sequences of the presentinvention: a reference nucleotide sequence preferably hybridizes to thereference nucleotide sequence in 7% sodium dodecyl sulfate (SDS), 0.5 MNaPO₄, 1 mM EDTA at 50° C. with washing in 2×SSC, 0.1% SDS at 50° C.,more desirably in 7% sodium dodecyl sulfate (SDS), 0.5 M NaPO₄, 1 mMEDTA at 50° C. with washing in 1×SSC, 0.1% SDS at 50° C., more desirablystill in 7% sodium dodecyl sulfate (SDS), 0.5 M NaPO₄, 1 mM EDTA at 50°C. with washing in 0.5×SSC, 0.1% SDS at 50° C., preferably in 7% sodiumdodecyl sulfate (SDS), 0.5 M NaPO₄, 1 mM EDTA at 50° C. with washing in0.1×SSC, 0.1% SDS at 50° C., more preferably in 7% sodium dodecylsulfate (SDS), 0.5 M NaPO₄, 1 mM EDTA at 50° C. with washing in 0.1×SSC,0.1% SDS at 65° C.

A further indication that two nucleic acid sequences or proteins aresubstantially identical is that the protein encoded by the first nucleicacid is immunologically cross reactive with, or specifically binds to,the protein encoded by the second nucleic acid. Thus, a protein istypically substantially identical to a second protein, for example,where the two proteins differ only by conservative substitutions.

“Synthetic” refers to a nucleotide sequence comprising structuralcharacters that are not present in the natural sequence. For example, anartificial sequence that resembles more closely the G+C content and thenormal codon distribution of dicot and/or monocot genes is said to besynthetic.

“Transformation” is a process for introducing heterologous nucleic acidinto a host cell or organism. In particular, “transformation” means thestable integration of a DNA molecule into the genome of an organism ofinterest.

“Transformed/transgenic/recombinant” refer to a host organism such as abacterium or a plant into which a heterologous nucleic acid molecule hasbeen introduced. The nucleic acid molecule can be stably integrated intothe genome of the host or the nucleic acid molecule can also be presentas an extrachromosomal molecule. Such an extrachromosomal molecule canbe auto-replicating. Transformed cells, tissues, or plants areunderstood to encompass not only the end product of a transformationprocess, but also transgenic progeny thereof. A “non-transformed”,“non-transgenic”, or “non-recombinant” host refers to a wild-typeorganism, e.g., a bacterium or plant, which does not contain theheterologous nucleic acid molecule.

The “Vip3 class of proteins” comprises, for example, without limitation,Vip3A(a), Vip3A(b), Vip3A(c), Vip3B, Vip3C(a), Vip3C(b), Vip3Z, andtheir homologues. “Homologue” is used herein to mean that the indicatedprotein or polypeptide bears a defined relationship to other members ofthe Vip3 class of proteins. This defined relationship includes but isnot limited to, 1) proteins which are at least 70%, more preferably atleast 80% and most preferably at least 90% identical at the sequencelevel to another member of the Vip3 class of proteins while alsoretaining pesticidal activity, 2) proteins which are cross-reactive toantibodies which immunologically recognize another member of the Vip3class of proteins, 3) proteins which are cross-reactive with a receptorto another member of the Vip3 class of proteins and retain the abilityto induce programmed cell death, and 4) proteins which are at least 70%,more preferably at least 80% and most preferably at least 90% identicalat the sequence level to the toxic core region of another member of theVip3 class of proteins while also retaining pesticidal activity. OtherVip3 homologues have been disclosed in WO 98/18932, WO 98/33991, WO98/00546, and WO 99/57282

Nucleotides are indicated by their bases by the following standardabbreviations: adenine (A), cytosine (C), thymine (T), and guanine (G).Amino acids are likewise indicated by the following standardabbreviations: alanine (Ala; A), arginine (Arg; R), asparagine (Asn; N),aspartic acid (Asp; D), cysteine (Cys; C), glutamine (Gln; Q), glutamicacid (Glu; E), glycine (Gly; G), histidine (His; H), isoleucine (Ile;l), leucine (Leu; L), lysine (Lys; K), methionine (Met; M),phenylalanine (Phe; F), proline (Pro; P), serine (Ser; S), threonine(Thr; T), tryptophan (Trp; W), tyrosine (Tyr; Y), and valine (Val; V).

DETAILED DESCRIPTION

This invention relates to nucleic acid sequences whose expressionresults in novel toxins, and to the making and using of the toxins tocontrol insect pests. The nucleic acid sequences are derived fromBacillus, a gram-positive spore-forming microorganism. In particular,novel Vip3 proteins, useful as pesticidal agents, are provided.

For purposes of the present invention, insect pests include insectsselected from the orders Coleoptera, Diptera, Hymenoptera, Lepidoptera,Mallophaga, Homoptera, Hemiptera, Orthroptera, Thysanoptera, Dermaptera,Isoptera, Anoplura, Siphonaptera, Trichoptera, etc., particularlyLepidoptera.

The expression of the nucleic acid sequences of the present inventionresults in toxins that can be used to control lepidopteran insects suchas Ostrinia nubilalis (European corn borer), Plutella xylostella(diamondback moth), Spodoptera frugiperda (fall armyworm), Agrotisipsilon (black cutworm), Helicoverpa zea (corn earworm), Heliothisvirescens (tobacco budworm), Spodoptera exigua (beet armyworm),Helicoverpa punctigera (native budworm), Helicoverpa armigera (cottonbollworm), Manduca sexta (tobacco hornworm), Trichoplusia ni (cabbagelooper), Pectinophora gossypiella (pink bollworm), and Cochylis hospes(banded sunflower moth).

In one embodiment, the invention encompasses an isolated nucleic acidmolecule comprising a nucleotide sequence that has at least 92% sequenceidentity with SEQ ID NO: 1, wherein expression of the isolated nucleicacid molecule results in insect control activity. When expressed in aheterologous host, the nucleic acid molecule of SEQ ID NO: 1 results ininsect control activity against Ostrinia nubilalis (European cornborer), Plutella xylostella (diamondback moth), Spodoptera frugiperda(fall armyworm), Agrotis ipsilon (black cutworm), Helicoverpa zea (cornearworm), Heliothis virescens (tobacco budworm), Spodoptera exigua (beetarmyworm), Helicoverpa punctigera (native budworm), Helicoverpa armigera(cotton bollworm), Manduca sexta (tobacco hornworm), Trichoplusia ni(cabbage looper), Pectinophora gossypiella (pink bollworm), and Cochylishospes (banded sunflower moth), showing that the nucleotide sequence setforth in SEQ ID NO: 1 is sufficient for such insect control activity. Ina further embodiment, the isolated nucleic acid molecule comprises anucleotide sequence that has at least 93% sequence identity with SEQ IDNO: 1. In a still further embodiment, the isolated nucleic acid moleculecomprises a nucleotide sequence that has at least 94% sequence identitywith SEQ ID NO: 1. In a still further embodiment, the isolated nucleicacid molecule comprises a nucleotide sequence that has at least 95%sequence identity with SEQ ID NO: 1. In a still further embodiment, theisolated nucleic acid molecule comprises a nucleotide sequence that hasat least 96% sequence identity with SEQ ID NO: 1. In a still furtherembodiment, the isolated nucleic acid molecule comprises a nucleotidesequence that has at least 97% sequence identity with SEQ ID NO: 1. In astill further embodiment, the isolated nucleic acid molecule comprises anucleotide sequence that has at least 98% sequence identity with SEQ IDNO: 1. In a still further embodiment, the isolated nucleic acid moleculecomprises a nucleotide sequence that has at least 99% sequence identitywith SEQ ID NO: 1. In a still further embodiment, the isolated nucleicacid molecule comprises the nucleotide sequence set forth in SEQ ID NO:1.

In another embodiment, the invention encompasses a nucleic acid moleculecomprised in pNOV1325, whose expression results in an insecticidaltoxin, which is deposited in the E. coli strain DH5α designated ATCCaccession number PTA-3868.

In one embodiment, the invention encompasses an isolated nucleic acidmolecule comprising a nucleotide sequence that is isocoding with anucleotide sequence that has at least 92% sequence identity with SEQ IDNO: 1, wherein expression of the isolated nucleic acid molecule resultsin insect control activity. When expressed in a heterologous host, thenucleic acid molecule of SEQ ID NO: 3 results in insect control activityagainst Ostrinia nubilalis (European corn borer), Plutella xylostella(diamondback moth), Spodoptera frugiperda (fall armyworm), Agrotisipsilon (black cutworm), Helicoverpa zea (corn earworm), Heliothisvirescens (tobacco budworm), Spodoptera exigua (beet armyworm),Helicoverpa punctigera (native budworm) and Helicoverpa armigera (cottonbollworm), showing that the nucleotide sequence set forth in SEQ ID NO:3 is sufficient for such insect control activity. In a furtherembodiment, the invention encompasses a nucleic acid molecule comprisedin pNOV1328, whose expression results in an insecticidal toxin, which isdeposited in the E. coli strain DH5α designated ATCC accession numberPTA-3869.

In another embodiment, the isolated nucleic acid molecule encodes atoxin comprising an amino acid sequence which has at least 91% sequenceidentity to the amino acid sequence set forth in SEQ ID NO: 2. In afurther embodiment, the isolated nucleic acid molecule encodes a toxincomprising an amino acid sequence which has at least 92% sequenceidentity to the amino acid sequence set forth in SEQ ID NO: 2. In astill further embodiment, the isolated nucleic acid molecule encodes atoxin comprising an amino acid sequence which has at least 93% sequenceidentity to the amino acid sequence set forth in SEQ ID NO: 2. In astill further embodiment, the isolated nucleic acid molecule encodes atoxin comprising an amino acid sequence which has at least 94% sequenceidentity to the amino acid sequence set forth in SEQ ID NO: 2. In astill further embodiment, the isolated nucleic acid molecule encodes atoxin comprising an amino acid sequence which has at least 95% sequenceidentity to the amino acid sequence set forth in SEQ ID NO: 2. In astill further embodiment, the isolated nucleic acid molecule encodes atoxin comprising an amino acid sequence which has at least 96% sequenceidentity to the amino acid sequence set forth in SEQ ID NO: 2. In astill further embodiment, the isolated nucleic acid molecule encodes atoxin comprising an amino acid sequence which has at least 97% sequenceidentity to the amino acid sequence set forth in SEQ ID NO: 2. In astill further embodiment, the isolated nucleic acid molecule encodes atoxin comprising an amino acid sequence which has at least 98% sequenceidentity to the amino acid sequence set forth in SEQ ID NO: 2. In astill further embodiment, the isolated nucleic acid molecule encodes atoxin comprising an amino acid sequence which has at least 99% sequenceidentity to the amino acid sequence set forth in SEQ ID NO: 2. In astill further embodiment, the isolated nucleic acid molecule encodes atoxin comprising the amino acid sequence set forth in SEQ ID NO: 2.

The present invention also encompasses recombinant vectors comprisingthe nucleic acid sequences of this invention. In such vectors, thenucleic acid sequences are preferably comprised in expression cassettescomprising regulatory elements for expression of the nucleotidesequences in a host cell capable of expressing the nucleotide sequences.Such regulatory elements usually comprise promoter and terminationsignals and preferably also comprise elements allowing efficienttranslation of polypeptides encoded by the nucleic acid sequences of thepresent invention. Vectors comprising the nucleic acid sequences areusually capable of replication in particular host cells, preferably asextrachromosomal molecules, and are therefore used to amplify thenucleic acid sequences of this invention in the host cells. In oneembodiment, host cells for such vectors are microorganisms, such asbacteria, in particular E. coli or Bacillus. In another embodiment, hostcells for such recombinant vectors are endophytes or epiphytes. Apreferred host cell for such vectors is a eukaryotic cell, such as ayeast cell, a plant cell, or an insect cell. Plant cells such as maizecells are most preferred host cells. In another preferred embodiment,such vectors are viral vectors and are used for replication of thenucleotide sequences in particular host cells, e.g. insect cells orplant cells. Recombinant vectors are also used for transformation of thenucleotide sequences of this invention into host cells, whereby thenucleotide sequences are stably integrated into the DNA of such hostcells. In one, such host cells are prokaryotic cells. In a preferredembodiment, such host cells are eukaryotic cells, such as yeast cells,insect cells, or plant cells. In a most preferred embodiment, the hostcells are plant cells, such as maize cells.

The present invention also provides a method of producing a toxin thatis active against insects, comprising (a) obtaining a transgenic hostcell according to the invention and (b) expressing a nucleic acidmolecule of the invention in the transgenic host cell which results inat least one toxin that is active against insects.

The present invention further provides a method of producing aninsect-resistant transgenic plant, comprising introducing a nucleic acidmolecule of the invention into the transgenic plant, wherein the nucleicacid molecule is expressible in the transgenic plant in an effectiveamount to control insects. In a still further embodiment the insects arelepidopteran insects. In a still further embodiment, the lepidopteraninsects are selected from the group consisting of Ostrinia nubilalis(European corn borer), Plutella xylostella (diamondback moth),Spodoptera frugiperda (fall armyworm), Agrotis ipsilon (black cutworm),Helicoverpa zea (corn earworm), Heliothis virescens (tobacco budworm),Spodoptera exigua (beet armyworm), Helicoverpa punctigera (nativebudworm), Helicoverpa armigera (cotton bollworm), Manduca sexta (tobaccohornworm), Trichoplusia ni (cabbage looper), Pectinophora gossypiella(pink bollworm), and Cochylis hospes (banded sunflower moth).

In another aspect, the present invention provides an isolated toxin thatis active against insects, wherein the toxin comprises an amino acidsequence that: (a) has at least 91% sequence identity with SEQ ID NO: 2;or (b) is encoded by a nucleic acid molecule comprising a nucleotidesequence that has at least 92% sequence identity with SEQ ID NO: 1.

In one embodiment, the present invention provides an isolated toxin thatis active against insects, wherein the toxin comprises an amino acidsequence that has at least 91% sequence identity with SEQ ID NO: 2. In afurther embodiment, the toxin comprises an amino acid sequence that hasat least 92% sequence identity with SEQ ID NO: 2. In a still furtherembodiment, the toxin has at least 93% sequence identity with SEQ ID NO:2. In a still further embodiment, the toxin has at least 94% sequenceidentity with SEQ ID NO: 2. In a still further embodiment, the toxin hasat least 95% sequence identity with SEQ ID NO: 2. In a still furtherembodiment, the toxin has at least 96% sequence identity with SEQ ID NO:2. In a still further embodiment, the toxin has at least 97% sequenceidentity with SEQ ID NO: 2. In a still further embodiment, the toxin hasat least 98% sequence identity with SEQ ID NO: 2. In a still furtherembodiment, the toxin has at least 99% sequence identity with SEQ ID NO:2. In a still further embodiment, the toxin comprises the amino acidsequence set forth in SEQ ID NO: 2.

In one embodiment, the present invention provides a toxin active againstinsects, wherein the toxin is produced by the expression of a nucleicacid molecule comprising a nucleotide sequence that has at least 92%sequence identity with SEQ ID NO: 1. In a further embodiment, thenucleotide sequence has at least 93% sequence identity with SEQ IDNO: 1. In a still further embodiment, the nucleotide sequence has atleast 94% sequence identity with SEQ ID NO: 1. In a still furtherembodiment, the nucleotide sequence has at least 95% sequence identitywith SEQ ID NO: 1. In a still further embodiment, the nucleotidesequence has at least 96% sequence identity with SEQ ID NO: 1. In astill further embodiment, the nucleotide sequence has at least 97%sequence identity with SEQ ID NO: 1. In a still further embodiment, thenucleotide sequence has at least 98% sequence identity with SEQ IDNO: 1. In a still further embodiment, the nucleotide sequence has atleast 99% sequence identity with SEQ ID NO: 1. In a still furtherembodiment, the toxin is produced by the expression of a nucleotidesequence comprising nucleotides 1-2364 of SEQ ID NO: 1 or nucleotides1-2364 of SEQ ID NO: 3.

In one embodiment, a toxin of the present invention is produced by theexpression of a nucleotide sequence comprising the approximately 2.4 kbDNA fragment comprised in pNOV1325, deposited as ATCC accession numberPTA-3868. In another embodiment, a toxin of the present invention isproduced by the expression of a nucleotide sequence comprising theapproximately 2.4 kb DNA fragment comprised in pNOV1328, deposited asATCC accession number PTA-3869.

In another embodiment, a toxin of the present invention is produced bythe E. coli strain designated as ATCC accession PTA-3868. In stillanother embodiment, the toxin is produced by the E. coli straindesignated as ATCC accession PTA-3869.

The toxins of the present invention have insect control activity whentested against insect pests in bioassays. In one embodiment, the toxinsof the invention are active against lepidopteran insects. In a furtherembodiment, the lepidopteran insects are selected from the groupconsisting of Ostrinia nubilalis (European corn borer), Plutellaxylostella (diamondback moth), Spodoptera frugiperda (fall armyworm),Agrotis ipsilon (black cutworm), Helicoverpa zea (corn earworm),Heliothis virescens (tobacco budworm), Spodoptera exigua (beetarmyworm), Helicoverpa punctigera (native budworm), Helicoverpa armigera(cotton bollworm), Manduca sexta (tobacco hornworm), Trichoplusia ni(cabbage looper), Pectinophora gossypiella (pink bollworm), and Cochylishospes (banded sunflower moth). The insect controlling properties of theinsecticidal toxins of the invention are further illustrated in Example5 and Example 8.

The present invention also encompasses hybrid toxins which are activeagainst insects, wherein the hybrid toxins are encoded by nucleic acidmolecules comprising a nucleotide sequence that: (a) has a complimentthat hybridizes to nucleotides 1734-2364 of SEQ ID NO: 1 in 7% sodiumdodecyl sulfate (SDS), 0.5 M NaPO₄, 1 mM EDTA at 50° C. with washing in0.1×SSC, 0.1% SDS at 65° C.; or (b) is isocoding with the nucleotidesequence of (a); or (c) comprises a consecutive 20 base pair nucleotideportion identical in sequence to a consecutive 20 base pair nucleotideportion of a nucleotide sequence of (a) or (b), wherein expression ofthe nucleic acid molecule results in insect control activity.Specifically exemplified herein is a hybrid toxin that is encoded by thenucleotide sequence set forth in SEQ ID NO: 6. When expressed in aheterologous host, the nucleic acid molecule of SEQ ID NO: 6 results ininsect control activity against Ostrinia nubilalis (European cornborer), Plutella xylostella (diamondback moth), Spodoptera frugiperda(fall armyworm), Agrotis ipsilon (black cutworm), Helicoverpa zea (cornearworm), Heliothis virescens (tobacco budworm), Spodoptera exigua (beetarmyworm), Pectinophora gossypiella (pink boll worm), Trichoplusia ni(cabbage looper), Cochyles hospes (banded sunflower moth), andHomoeosoma electellum (sunflower head moth).

The present invention also encompasses hybrid toxins active againstinsects that comprise a carboxy-terminal region of a Vip3 toxin joinedin the amino to carboxy direction to an amino-terminal region of adifferent Vip3 toxin, wherein the carboxy-terminal region comprises anamino acid sequence which has at least 75% identity with amino acids579-787 of SEQ ID NO: 2; and wherein the amino-terminal region has atleast 75% identity with amino acids 1-578 of SEQ ID NO: 5. In a furtherembodiment, the carboxy-terminal region comprises amino acids 579-787 ofSEQ ID NO: 2, and the amino-terminal region comprises amino acids 1-578of SEQ ID NO: 5. In a still further embodiment, the hybrid toxincomprises amino acids 1-787 of SEQ ID NO: 6.

Expression of the Nucleotide Sequences in Heterologous Microbial Hosts

As biological insect control agents, the insecticidal toxins areproduced by expression of the nucleotide sequences in heterologous hostcells capable of expressing the nucleotide sequences. In a firstembodiment, B. thuringiensis cells comprising modifications of anucleotide sequence of this invention are made. Such modificationsencompass mutations or deletions of existing regulatory elements, thusleading to altered expression of the nucleotide sequence, or theincorporation of new regulatory elements controlling the expression ofthe nucleotide sequence. In another embodiment, additional copies of oneor more of the nucleotide sequences are added to Bacillus thuringiensiscells either by insertion into the chromosome or by introduction ofextrachromosomally replicating molecules containing the nucleotidesequences.

In another embodiment, at least one of the nucleotide sequences of theinvention is inserted into an appropriate expression cassette,comprising a promoter and termination signals. Expression of thenucleotide sequence is constitutive, or an inducible promoter respondingto various types of stimuli to initiate transcription is used. In apreferred embodiment, the cell in which the toxin is expressed is amicroorganism, such as a virus, a bacteria, or a fungus. In a preferredembodiment, a virus, such as a baculovirus, contains a nucleotidesequence of the invention in its genome and expresses large amounts ofthe corresponding insecticidal toxin after infection of appropriateeukaryotic cells that are suitable for virus replication and expressionof the nucleotide sequence. The insecticidal toxin thus produced is usedas an insecticidal agent. Alternatively, baculoviruses engineered toinclude the nucleotide sequence are used to infect insects in vivo andkill them either by expression of the insecticidal toxin or by acombination of viral infection and expression of the insecticidal toxin.

Bacterial cells are also hosts for the expression of the nucleotidesequences of the invention. In a preferred embodiment, non-pathogenicsymbiotic bacteria, which are able to live and replicate within planttissues, so-called endophytes, or non-pathogenic symbiotic bacteria,which are capable of colonizing the phyllosphere or the rhizosphere,so-called epiphytes, are used. Such bacteria include bacteria of thegenera Agrobacterium, Alcaligenes, Azospirillum, Azotobacter, Bacillus,Clavibacter, Enterobacter, Erwinia, Flavobacter, Klebsiella,Pseudomonas, Rhizobium, Serratia, Streptomyces and Xanthomonas.Symbiotic fungi, such as Trichodenna and Gliocladium are also possiblehosts for expression of the inventive nucleotide sequences for the samepurpose.

Techniques for these genetic manipulations are specific for thedifferent available hosts and are known in the art. For example, theexpression vectors pKK223-3 and pKK223-2 can be used to expressheterologous genes in E. coli, either in transcriptional ortranslational fusion, behind the tac or trc promoter. For the expressionof operons encoding multiple ORFs, the simplest procedure is to insertthe operon into a vector such as pKK223-3 in transcriptional fusion,allowing the cognate ribosome binding site of the heterologous genes tobe used. Techniques for overexpression in gram-positive species such asBacillus are also known in the art and can be used in the context ofthis invention (Quax et al. In:Industrial Microorganisms:Basic andApplied Molecular Genetics, Eds. Baltz et al., American Society forMicrobiology, Washington (1993)). Alternate systems for overexpressionrely for example, on yeast vectors and include the use of Pichia,Saccharomyces and Kluyveromyces (Sreekrishna, In:Industrialmicroorganisms:basic and applied molecular genetics, Baltz, Hegeman, andSkatrud eds., American Society for Microbiology, Washington (1993);Dequin & Barre, Biotechnology L2:173-177 (1994); van den Berg et al.,Biotechnology 8:135-139 (1990)).

Plant Transformation

In a particularly preferred embodiment, at least one of the insecticidaltoxins of the invention is expressed in a higher organism, e.g., aplant. In this case, transgenic plants expressing effective amounts ofthe toxins protect themselves from insect pests. When the insect startsfeeding on such a transgenic plant, it also ingests the expressedtoxins. This will deter the insect from further biting into the planttissue or may even harm or kill the insect. A nucleotide sequence of thepresent invention is inserted into an expression cassette, which is thenpreferably stably integrated in the genome of said plant. In anotherpreferred embodiment, the nucleotide sequence is included in a non-pathogenic self-replicating virus. Plants transformed in accordance withthe present invention may be monocots or dicots and include, but are notlimited to, maize, wheat, barley, rye, sweet potato, bean, pea, chicory,lettuce, cabbage, cauliflower, broccoli, turnip, radish, spinach,asparagus, onion, garlic, pepper, celery, squash, pumpkin, hemp,zucchini, apple, pear, quince, melon, plum, cherry, peach, nectarine,apricot, strawberry, grape, raspberry, blackberry, pineapple, avocado,papaya, mango, banana, soybean, tomato, sorghum, sugarcane, sugar beet,sunflower, rapeseed, clover, tobacco, carrot, cotton, alfalfa, rice,potato, eggplant, cucumber, Arabidopsis, and woody plants such asconiferous and deciduous trees.

Once a desired nucleotide sequence has been transformed into aparticular plant species, it may be propagated in that species or movedinto other varieties of the same species, particularly includingcommercial varieties, using traditional breeding techniques.

A nucleotide sequence of this invention is preferably expressed intransgenic plants, thus causing the biosynthesis of the correspondingtoxin in the transgenic plants. In this way, transgenic plants withenhanced resistance to insects are generated. For their expression intransgenic plants, the nucleotide sequences of the invention may requiremodification and optimization. Although in many cases genes frommicrobial organisms can be expressed in plants at high levels withoutmodification, low expression in transgenic plants may result frommicrobial nucleotide sequences having codons that are not preferred inplants. It is known in the art that all organisms have specificpreferences for codon usage, and the codons of the nucleotide sequencesdescribed in this invention can be changed to conform with plantpreferences, while maintaining the amino acids encoded thereby.Furthermore, high expression in plants is best achieved from codingsequences that have at least about 35% GC content, preferably more thanabout 45%, more preferably more than about 50%, and most preferably morethan about 60%. Microbial nucleotide sequences that have low GC contentsmay express poorly in plants due to the existence of ATTTA motifs thatmay destabilize messages, and AATAAA motifs that may cause inappropriatepolyadenylation. Although preferred gene sequences may be adequatelyexpressed in both monocotyledonous and dicotyledonous plant species,sequences can be modified to account for the specific codon preferencesand GC content preferences of monocotyledons or dicotyledons as thesepreferences have been shown to differ (Murray et al. Nucl. Acids Res.17:477-498 (1989)). In addition, the nucleotide sequences are screenedfor the existence of illegitimate splice sites that may cause messagetruncation. All changes required to be made within the nucleotidesequences such as those described above are made using well knowntechniques of site directed mutagenesis, PCR, and synthetic geneconstruction using the methods described in the published patentapplications EP 0 385 962, EP 0 359 4721, and WO 93/07278.

In one embodiment of the invention the vip3B gene is made according tothe procedure disclosed in U.S. Pat. No. 5,625,136, herein incorporatedby reference. In this procedure, maize preferred codons, i.e., thesingle codon which most frequently encodes that amino acid in maize, areused. The maize preferred codon for a particular amino acid may bederived, for example, from known gene sequences from maize. Maize codonusage for 28 genes from maize plants is found in Murray et al., NucleicAcids Research 17:477-498 (1989), the disclosure of which isincorporated herein by reference. A synthetic sequence made with maizeoptimized codons is set forth in SEQ ID NO: 2.

In this manner, the nucleotide sequences can be optimized for expressionin any plant. It is recognized that all or any part of the gene sequencemay be optimized or synthetic. That is, synthetic or partially optimizedsequences may also be used.

For efficient initiation of translation, sequences adjacent to theinitiating methionine may require modification. For example, they can bemodified by the inclusion of sequences known to be effective in plants.Joshi has suggested an appropriate consensus for plants (NAR15:6643-6653 (1987)) and Clonetech suggests a further consensustranslation initiator (1993/1994 catalog, page 210). These consensusesare suitable for use with the nucleotide sequences of this invention.The sequences are incorporated into constructions comprising thenucleotide sequences, up to and including the ATG (whilst leaving thesecond amino acid unmodified), or alternatively up to and including theGTC subsequent to the ATG (with the possibility of modifying the secondamino acid of the transgene).

The novel vip3 toxin genes of the present invention, either as theirnative sequence or as optimized synthetic sequences as described above,can be operably fused to a variety of promoters for expression in plantsincluding constitutive, inducible, temporally regulated, developmentallyregulated, chemically regulated, tissue-preferred and tissue-specificpromoters to prepare recombinant DNA molecules, i.e., chimeric genes.The choice of promoter will vary depending on the temporal and spatialrequirements for expression, and also depending on the target species.Thus, expression of the nucleotide sequences of this invention inleaves, in stalks or stems, in ears, in inflorescences (e.g. spikes,panicles, cobs, etc.), in roots, and/or seedlings is preferred. In manycases, however, protection against more than one type of insect pest issought, and thus expression in multiple tissues is desirable. Althoughmany promoters from dicotyledons have been shown to be operational inmonocotyledons and vice versa, ideally dicotyledonous promoters areselected for expression in dicotyledons, and monocotyledonous promotersfor expression in monocotyledons. However, there is no restriction tothe provenance of selected promoters; it is sufficient that they areoperational in driving the expression of the nucleotide sequences in thedesired cell.

Preferred constitutive promoters include the CaMV 35S and 19S promoters(Fraley et al., U.S. Pat. No. 5,352,605 issued Oct. 4, 1994). Anadditionally preferred promoter is derived from any one of several ofthe actin genes, which are expressed in most cell types. The promoterexpression cassettes described by McElroy et al. (Mol. Gen. Genet. 231:150-160 (1991)) can be easily modified for the expression of the noveltoxin gene and are particularly suitable for use in monocotyledonoushosts.

Yet another preferred constitutive promoter is derived from ubiquitin,which is another gene product known to accumulate in many cell types. Aubiquitin promoter has been cloned from several species for use intransgenic plants, for example, sunflower (Binet et al., 1991. PlantScience 79: 87-94), maize (Christensen et al., 1989. Plant Molec. Biol.12: 619-632), and Arabidopsis (Norris et al. 1993. Plant Molec. Biol.21:895-906). The maize ubiquitin promoter (UbiP) has been developed intransgenic monocot systems and its sequence and vectors constructed formonocot transformation are disclosed in the patent publication EP 0 342926. The ubiquitin promoter is suitable for the expression of the noveltoxin gene in transgenic plants, especially monocotyledons.

Tissue-specific or tissue-preferential promoters useful for theexpression of the novel toxin genes of the invention in plants,particularly maize, are those that direct expression in root, pith, leafor pollen. Such promoters are disclosed in WO 93/07278, hereinincorporated by reference in its entirety. Other tissue specificpromoters useful in the present invention include the cotton rubiscopromoter disclosed in U.S. Pat. No. 6,040,504; the rice sucrose synthasepromoter disclosed in U.S. Pat. No. 5,604,121; and the cestrum yellowleaf curling virus promoter disclosed in WO 01/73087, all incorporatedby reference. Chemically inducible promoters useful for directing theexpression of the novel toxin gene in plants are disclosed in U.S. Pat.No. 5,614,395 herein incorporated by reference in its entirety.

The nucleotide sequences of this invention can also be expressed underthe regulation of promoters that are chemically regulated. This enablesthe Vip3 toxins to be synthesized only when the crop plants are treatedwith the inducing chemicals. Preferred technology for chemical inductionof gene expression is detailed in the published application EP 0 332 104(to Ciba- Geigy) and U.S. Pat. No. 5,614,395. A preferred promoter forchemical induction is the tobacco PR-1a promoter.

A preferred category of promoters is that which is wound inducible.Numerous promoters have been described which are expressed at woundsites and also at the sites of phytopathogen infection. Ideally, such apromoter should only be active locally at the sites of infection, and inthis way the insecticidal toxins only accumulate in cells that need tosynthesize the insecticidal toxins to kill the invading insect pest.Preferred promoters of this kind include those described by Stanford etal. Mol. Gen. Genet. 215:200-208 (1989), Xu et al. Plant Molec. Biol.22:573-588 (1993), Logemann et al. Plant Cell 1:151-158 (1989),Rohrmeier & Lehle, Plant Molec. Biol. 22:783-792 (1993), Firek et al.Plant Molec. Biol. 22:129-142 (1993), and Warner et al. Plant J.3:191-201 (1993).

Preferred tissue specific expression patterns include green tissuespecific, root specific, stem specific, and flower specific. Promoterssuitable for expression in green tissue include many that regulate genesinvolved in photosynthesis and many of these have been cloned from bothmonocotyledons and dicotyledons. A preferred promoter is the maize PEPCpromoter from the phosphoenol carboxylase gene (Hudspeth & Grula, PlantMolec. Biol. 12:579-589 (1989)). A preferred promoter for root specificexpression is that described by de Framond (FEBS 290:103-106 (1991); EP0 452 269 to Ciba-Geigy). A preferred stem specific promoter is thatdescribed in U.S. Pat. No. 5,625,136 (to Ciba-Geigy) and which drivesexpression of the maize trpA gene.

Further preferred embodiments are transgenic plants expressing thenucleotide sequences in a wound-inducible or pathogeninfection-inducible manner.

In addition to the selection of a suitable promoter, constructions forexpression of an insecticidal toxin in plants require an appropriatetranscription terminator to be attached downstream of the heterologousnucleotide sequence. Several such terminators are available and known inthe art (e.g. trml from CaMV, E9 from rbcS). Any available terminatorknown to function in plants can be used in the context of thisinvention.

Numerous other sequences can be incorporated into expression cassettesdescribed in this invention. These include sequences that have beenshown to enhance expression such as intron sequences (e.g. from Adhl andbronzel) and viral leader sequences (e.g. from TMV, MCMV and AMV).

It may be preferable to target expression of the nucleotide sequences ofthe present invention to different cellular localizations in the plant.In some cases, localization in the cytosol may be desirable, whereas inother cases, localization in some subcellular organelle may bepreferred. Subcellular localization of transgene-encoded enzymes isundertaken using techniques well known in the art. Typically, the DNAencoding the target peptide from a known organelle-targeted gene productis manipulated and fused upstream of the nucleotide sequence. Many suchtarget sequences are known for the chloroplast and their functioning inheterologous constructions has been shown. The expression of thenucleotide sequences of the present invention is also targeted to theendoplasmic reticulum or to the vacuoles of the host cells. Techniquesto achieve this are well known in the art.

Vectors suitable for plant transformation are described elsewhere inthis specification. For Agrobacterium-mediated transformation, binaryvectors or vectors carrying at least one T-DNA border sequence aresuitable, whereas for direct gene transfer any vector is suitable andlinear DNA containing only the construction of interest may bepreferred. In the case of direct gene transfer, transformation with asingle DNA species or co-transformation can be used (Schocher et al.Biotechnology 4:1093-1096 (1986)). For both direct gene transfer andAgrobacterium-mediated transfer, transformation is usually (but notnecessarily) undertaken with a selectable marker that may provideresistance to an antibiotic (kanamycin, hygromycin or methotrexate) or aherbicide (basta). The choice of selectable marker is not, however,critical to the invention.

In another preferred embodiment, a nucleotide sequence of the presentinvention is directly transformed into the plastid genome. A majoradvantage of plastid transformation is that plastids are generallycapable of expressing bacterial genes without substantial modification,and plastids are capable of expressing multiple open reading framesunder control of a single promoter. Plastid transformation technology isextensively described in U.S. Pat. Nos. 5,451,513, 5,545,817, and5,545,818, in PCT application no. WO 95/16783, and in McBride et aL(1994) Proc. Nati. Acad. Sci. USA 91, 7301-7305. The basic technique forchloroplast transformation involves introducing regions of clonedplastid DNA flanking a selectable marker together with the gene ofinterest into a suitable target tissue, e.g., using biolistics orprotoplast transformation (e.g., calcium chloride or PEG mediatedtransformation). The 1 to 1.5 kb flanking regions, termed targetingsequences, facilitate homologous recombination with the plastid genomeand thus allow the replacement or modification of specific regions ofthe plastome. Initially, point mutations in the chloroplast 16S rRNA andrps 12 genes conferring resistance to spectinomycin and/or streptomycinare utilized as selectable markers for transformation (Svab, Z.,Hajdukiewicz, P., and Maliga, P. (1990) Proc. Nati. Acad. Sci. USA 87,8526-8530; Staub, J. M., and Maliga, P. (1992) Plant Cell 4, 39-45).This resulted in stable homoplasmic transformants at a frequency ofapproximately one per 100 bombardments of target leaves. The presence ofcloning sites between these markers allowed creation of a plastidtargeting vector for introduction of foreign genes (Staub, J. M., andMaliga, P. (1993) EMBO J. 12, 601-606). Substantial increases intransformation frequency are obtained by replacement of the recessiverRNA or r-protein antibiotic resistance genes with a dominant selectablemarker, the bacterial aadA gene encoding the spectinomycin-cletoxifyingenzyme aminoglycoside-3′-adenyltransferase (Svab, Z., and Maliga, P.(1993) Proc. Natl. Acad. Sci. USA 90, 913-917). Previously, this markerhad been used successfully for high-frequency transformation of theplastid genome of the green alga Chlamydomonas reinhardtii(Goldschmidt-Clermont, M. (1991) Nucl. Acids Res. 19:4083-4089). Otherselectable markers useful for plastid transformation are known in theart and encompassed within the scope of the invention. Typically,approximately 15-20 cell division cycles following transformation arerequired to reach a homoplastidic state. Plastid expression, in whichgenes are inserted by homologous recombination into all of the severalthousand copies of the circular plastid genome present in each plantcell, takes advantage of the enormous copy number advantage overnuclear- expressed genes to permit expression levels that can readilyexceed 10% of the total soluble plant protein. In a preferredembodiment, a nucleotide sequence of the present invention is insertedinto a plastid-targeting vector and transformed into the plastid genomeof a desired plant host. Plants homoplastic for plastid genomescontaining a nucleotide sequence of the present invention are obtained,and are preferentially capable of high expression of the nucleotidesequence.

Combinations of Insect Control Principles

The pesticidal toxins of the invention can be used in combination withBt δ-endotoxins or other pesticidal principles to increase pest targetrange. Furthermore, the use of the pesticidal toxins of the invention incombination with Bt δ-endotoxins or other pesticidal principles of adistinct nature has particular utility for the prevention and/ormanagement of insect resistance.

The various insecticidal crystal proteins from Bacillus thuringiensishave been classified based upon their spectrum of activity and sequencesimilarity. The classification put forth by Hofte and Whiteley,Microbiol. Rev. 53: 242-255 (1989) placed the then known insecticidalcrystal proteins into four major classes. Generally, the major classesare defined by the spectrum of activity, with the Cry1 proteins activeagainst Lepidoptera, Cry2 proteins active against both Lepidoptera andDiptera, Cry3 proteins active against Coleoptera, and Cry4 proteinsactive against Diptera.

Within each major class, the δ-endotoxins are grouped according tosequence similarity. The Cry1 proteins are typically produced as 130-140kDa protoxin proteins that are proteolytically cleaved to produce activetoxins that are about 60-70 kDa. The active portion of the δ-endotoxinresides in the NH₂-terminal portion of the full-length molecule. Hofteand Whiteley, supra, classified the then known Cry1 proteins into sixgroups, 1Aa, 1Ab, 1Ac, 1B, 1C, and 1D. Since then, proteins classifiedas Cry1Ea, Cry1Fa, Cry9A, Cry9C and Cry9B, as well as others, have alsobeen characterized.

The spectrum of insecticidal activity of an individual δ-endotoxin fromBacillus thuringiensis tends to be quite narrow, with a givenδ-endotoxin being active against only a few insects. Specificity is theresult of the efficiency of the various steps involved in producing anactive toxin protein and its subsequent ability to interact with theepithelial cells in the insect digestive tract. In one preferredembodiment, expression of the nucleic acid molecules of the invention intransgenic plants is accompanied by the expression of one or more Btδ-endotoxins. Particularly preferred Bt δ-endotoxins are those disclosedin U.S. Pat. No. 5,625,136, herein incorporated by reference.

It is well known that many δ-endotoxin proteins from Bacillusthuringiensis are actually expressed as protoxins. These protoxins aresolubilized in the alkaline environment of the insect gut and areproteolytically converted by proteases into a toxic core fragment (Hofteand Whiteley, Microbiol. Rev. 53: 242-255 (1989)). For δ-endotoxinproteins of the Cry1 class, the toxic core fragment is localized in theN-terminal half of the protoxin. It is within the scope of the presentinvention that genes encoding either the full-length protoxin form orthe truncated toxic core fragment of the novel toxin proteins can beused in plant transformation vectors to confer insecticidal propertiesupon the host plant.

Other insecticidal principles include protease inhibitors (both serineand cysteine types), lectins, α-amylase, peroxidase and cholesteroloxidase. Other Vip coding sequences, such as vip1A(a) and vip2A(a) asdisclosed in U.S. Pat. No. 5,849,870 and herein incorporated byreference, are also useful in the present invention.

This co-expression of more than one insecticidal principle in the sametransgenic plant can be achieved by genetically engineering a plant tocontain and express all the genes necessary. Alternatively, a plant,Parent 1, can be genetically engineered for the expression of genes ofthe present invention. A second plant, Parent 2, can be geneticallyengineered for the expression of a supplemental insect controlprinciple. By crossing Parent 1 with Parent 2, progeny plants areobtained which express all the genes introduced into Parents 1 and 2.

The present invention further encompasses variants of the disclosednucleic acid molecules. Naturally occurring variant sequences can beidentified and/or isolated with the use of well-known molecular biologytechniques, as, for example, with PCR and hybridization techniques asoutlined below.

Variant vip3 nucleotide sequences include synthetically derivednucleotide sequences, such as those generated, for example, by usingsite-directed mutagenesis or those made by whole domain swaps, but whichstill exhibit pesticidal activity. Methods for mutagenesis andnucleotide sequence alterations are well known in the art. See, forexample, Kunkel (1985) Proc. Natl. Acad. Sci. USA 82:488-492; Kunkel etal. (1987) Methods in Enzymol. 154:367-382; U.S. Pat. No. 4,873,192;Walker and Gaastra, eds. (1983) Techniques in Molecular Biology(MacMillan Publishing Company, New York) and the references citedtherein. Generally, a nucleotide sequence of the invention will have atleast 80%, preferably 85%, 90%, 95%, up to 98% or more sequence identityto its respective reference vip3 nucleotide sequence, and havepesticidal activity.

Variant vip3 nucleotide sequences also encompass sequences derived froma mutagenic and recombinogenic procedure such as DNA shuffling. Withsuch a procedure, one or more different vip3 sequences of the presentinvention, for example, without limitation, vip3B and vip3A-B can berecombined together or with other vip3 or related sequences, forexample, and without limitation, vip3A (SEQ ID NO: 5), to create newvip3 nucleic acid molecules encoding Vip3 toxins possessing the desiredproperties. In this manner, libraries of recombinant vip3polynucleotides are generated from a population of sequence related vip3polynucleotides comprising sequence regions that have substantialsequence identity and can be homologously recombined in vitro or invivo. Strategies for such DNA shuffling are known in the art. See, forexample, Stemmer (1994) Proc. Natl. Acad. Sci. USA 91:10747-10751;Stemmer (1994) Nature 370:389-391; Crameri et al. (1997) Nature Biotech.15:436-438; Moore et al. (1997) J. Mol. Biol. 272:336-347; Zhang et al.(1997) Proc. Natl. Acad. Sci. USA 94:4504-4509; Crameri et al. (1998)Nature 391:288-291; International Patent Application WO 99/57128, andU.S. Pat. Nos. 5,605,793, 5,837,458 and 6,335,179.

Mutagenesis methods as disclosed herein can be combined withhigh-throughput, screening methods to detect the pesticidal activity ofcloned, mutagenized Vip3 polypeptides in host cells. Mutagenized DNAmolecules that encode active Vip3 polypeptides (e.g., secreted anddetected by antibodies; or insecticidal in an insect bioassay) can berecovered from the host cells and rapidly sequenced using standard artprocedures. These methods allow the rapid determination of theimportance of individual amino acid residues in a Vip3 polypeptide ofinterest, and can be applied to polypeptides of unknown structure.

The libraries of recombinant vip3 genes that are produced using DNAshuffling methods are screened to identify those that exhibit improvedproperties for use in protecting plants against pests. Included amongproperties for which DNA shuffling is useful for obtaining improved vip3pest resistance genes are increased potency against a target pest,increased target pest range, decreased susceptibility to development ofresistance by pests, increased expression level, increased resistance toprotease degradation, increased stability in environmental conditions,and reduced toxicity to a host plant. By using an appropriate screeningstrategy, one can simultaneously or sequentially obtain vip3 genes thatare optimized for more than one property.

DNA shuffling is useful for obtaining vip3 pest resistance genes thatencode toxins that exhibit enhanced potency against a target pest. Oncethe shuffling is completed, the resulting library of shuffled vip3 genesis screened to identify those that exhibit enhanced pesticidal activity.One way of performing this screening is to clone the protein-codingregion of the shuffled vip3 genes into an expression vector that issuitable for expressing the genes in a chosen host cell such as, forexample, E. coli or a crystal minus strain of Bacillus thuringiensis.One skilled in the art will recognize the advantages and disadvantagesof using either of these two expression systems. For example, Bacillusthuringiensis would be more desirable in producing secreted Vip3proteins. If desired, clones can be subjected to a preliminary screen,for example, by immunoassay, to identify those that produce a Vip3protein of the correct size. Those that are positive in the preliminaryscreen are then tested in a functional screen to identify shuffled vip3genes that encode a toxin having the desired enhanced activity.

A whole insect assay can be used for determining toxicity. In theseassays, the Vip3 toxins expressed from the shuffled vip3 genes areplaced on insect diet, for example, artificial diet or plant tissue, andconsumed by the target insect. Those clones causing growth inhibition ormortality to the target insect can be tested in further bioassays todetermine potency. Shuffled vip3 genes encoding toxins with enhancedpotency can be identified as those that have a decreased EC₅₀(concentration of toxin necessary to reduce insect growth by 50%) and/orLC₅₀ (concentration of toxin necessary to cause 50% mortality).

In vitro assays can also be used for screening shuffled Vip3 genelibraries. Such assays typically involve the use of cultured insectcells that are susceptible to Vip3 toxins, and/or cells that express areceptor for the Vip3 toxins, either naturally or as a result ofexpression of a heterologous gene. Other in vitro assays can be used,for example, detection of morphological changes in cells, dyes andlabels useful for detecting cell death, or detection of the release ofATPase by cells. One example of a suitable in vitro assay using culturedinsect cells for Vip3 toxicity is Sf9 (Spodoptera frugiperda) cells. Sf9is highly sensitive to Vip3 toxins. When Vip3 toxins are mixed with Sf9cells, the cell membrane becomes highly permeable to small molecules.When a dye such as trypan blue is added to the cell suspension, thosecells which are killed by the Vip3 toxin are stained blue. Thus, thecytotoxicity of the Vip3 toxin can be determined by image analysis.

Additional in vitro assays involve the use of receptors for the Vip3toxins. One such receptor is disclosed in U.S. Pat. No. 6,291,156,herein incorporated by reference. The Vip3 receptor protein can beimmobilized on a receiving surface, for example, without limitation, a96-well plate or a nitrocellulose membrane, and exposed to clonescomprising shuffled vip3 genes. Thus, shuffled vip3 genes that encodefunctional toxins can be identified on the basis of binding affinity tothe Vip3 receptor. Further, the gene encoding the Vip3 receptor can betransformed into a non-Vip3 susceptible cell line, for example theSchneider 2 (S2) Drosophila cell line, using methods known in the art(see for example, Clem and Miller, 1194, Mol. Cel. Biol. 14:5212-522).The transformed S2 cells can then be exposed to clones comprisingshuffled vip3 genes. Thus, shuffled vip3 genes that encode functionaltoxins can be identified on the basis of induction of cell death.

EXAMPLES

The invention will be further described by reference to the followingdetailed examples. These examples are provided for the purposes ofillustration only, and are not intended to be limiting unless otherwisespecified. Standard recombinant DNA and molecular cloning techniquesused here are well known in the art and are described by Ansubel (ed.)Current Protocols in Molecular Biology, John Wiley and Sons, Inc.(1994); T. Maniatis, E. F. Fritsch and J. Sambrook, Molecular Cloning: ALaboratory Manual, Cold Spring Harbor laboratory, Cold Spring Harbor,N.Y. (1998); and by T. J. Silhavy, M. L. Berman, and L. W. Enquist,Experiments with Gene Fusions, Cold Spring Harbor Laboratory, ColdSpring Harbor, N.Y. (1984).

Example 1 Construction of Cosmid Library from Bacillus thuringiensisStrain AB1183

Total DNA was isolated from a Bacillus thuringiensis strain, designatedAB1183, by treating freshly grown cells resuspended in 100 mM Tris pH 8,10 mM EDTA with 2 mg/ml lysozyme for 30 minutes at 37° C. Proteinase Kwas added to a final concentration of 100 μg/ml in 1% SDS, 50 mM EDTA,1M urea and incubated at 55° C. An equal volume ofphenol-chloroform-isoamyl alcohol was added. The sample was gently mixedfor 5 minutes and centrifuged at 3K. This was repeated twice. Theaqueous phase was then mixed with 0.7 volumes isopropanol andcentrifuged. The DNA pellet was washed three times with 70% ethanol andgently resuspended in 0.5×TE. 12 μg of DNA was treated with 0.3 unit ofSau3A per μg of DNA at 37° C. in a volume of 100 μl. Samples were takenat 2-min intervals for 10 minutes. Then 1/10 volume 10×TE was added andsamples were then heated for 30 minutes at 65° C. to inactivate theenzyme. The samples were subjected to electrophoresis to determine whichfraction was in the 40-kb range and this sample was used in theligation.

SuperCos cosmid vector (Stratagene, La Jolla, Calif.) was prepared asdescribed by the supplier utilizing the BamHI cloning site. PreparedSupercos at 100 ηg/ml was ligated with the AB1183 DNA previouslydigested with Sau3A at a ratio of 2:1 in a 5 μl volume overnight at 6°C. The ligation mixture was packaged using Gigapack XL III (Stratagene)as described by the supplier. Packaged phages were infected into XL-1MRE. coli cells (Stratagene) as described by the supplier. The cosmidlibrary was plated on L-agar with 50 μg/ml kanamycin and incubated 16hours at 37° C. 1200 colonies were picked and grown for testing againstinsects.

Example 2 Bioassay of Cosmid Clones

The 1200 colonies from Example 1 were screened for insecticidal activityagainst Heliothis virescens neonate larvae. The bioassay was performedusing a surface contamination method on artificial diet. The bioassaywas scored after 7 days. Eight clones were found to be insecticidal toHeliothis virescens.

Example 3 Analysis of Insecticidal Cosmid Clones

To identify vip3 homologous sequences, PCR analysis was performed on theeight Heliothis virescens-positive clones using primers from the 5′prime region of the vip3A gene (SEQ ID NO: 4), using the methods ofCarozzi et al. (1991, Appl. Env. Microbiol. 57: 3057-3061). The primersused for this analysis are:

Forward: 5′-GTGATCTAACCCTAGACG-3′ (SEQ ID NO: 8) Reverse:5′-GCTTTAGTTCCATTCACTCC-3′. (SEQ ID NO: 9)

One clone produced a DNA band of the size expected for genes related tothe vip3 class. A 3.8 kb EcoRI fragment from this clone was subclonedinto pBluescript (Stratagene) and transformed into E. coli. This E. coliclone was confirmed to comprise a vip3 homologous coding sequence usingPCR analysis. The vip3 homologous coding sequence was designated vip3B.Bioassay results of the E. coli clone comprising the vip3B codingsequence demonstrated that the Vip3B toxin was responsible for theHeliothis virescens activity. The plasmid comprised in this clone, andthe clone, were designated pCIB9400.

Example 4 Cloning and Sequencing the Full-length vip3B Gene

pCIB9400 was cut with BglII and EcoRV to remove approximately 800 bp offlanking sequence near the 3′ end of the vip3B coding sequence. The endsof the resulting fragment were filled in using Klenow polymerase (NewEngland Biolabs, Beverly, Mass.) and then ligated together using T4ligase (New England Biolabs, Beverly, Mass.) This ligation mixture wastransformed into E. coli DH5α cells. Plasmid DNA was isolated fromsingle colonies using a standard alkaline lysis procedure and severalrestriction digests were done to ensure that the 800 bp flanking regionwas deleted. The resulting plasmid was designated pNOV1325 and depositedin E. coli as ATCC accession no. PTA-3868.

Sequencing was performed using the dideoxy chain-termination method andwas completed using Applied Biosystems Inc. model 3700 automated DNAsequencer (Foster City, Calif.). The sequence was assembled usingSequencher 4.05 from Gene Codes Corporation (Ann Arbor, Mich.).

Sequence analysis identified a 2364 bp coding sequence (SEQ ID NO: 1)coding for a 787 amino acid protein (SEQ ID NO: 2) with an approximatemolecular weight of 88 kDa. The vip3B nucleotide sequence has 86%identity to the nucleotide sequence of the vip3A gene. The amino acidsequence of the Vip3B protein is 81% identical to the amino acidsequence of the Vip3A protein.

Example 5 Bioassay of the Vip3B Protein Expressed in pNOV1325 andpCIB9400

Molten black cutworm diet (BioServ, Frenchtown, N.J.) was poured into 50mm petri dishes and allowed to solidify. A 200 μl suspension of Top10(Invitrogen,) E. coli cells comprising either pNOV1325 or pNOV9400 (eachof which comprise the vip3B coding sequence) was pipetted onto the dietsurface. The solution was uniformly spread with a bacterial loop so thatthe suspension covered the entire surface of the diet. The surface wasallowed to dry thoroughly. First instar larvae of a lepidopteran specieslisted in the table below were placed on the diet with a fine tip brush.Each species was tested separately. Larval mortality was recorded at 3days and 5 days after larval infestation of the diet. A samplecontaining Top10 E. coli cells without a vector was used for thenegative control. Vip3A protein can also be tested in the same bioassayfor comparative purposes. For this example, the Vip3B data obtained inthis example were compared with the known activity spectrum data ofVip3A.

The bioassay results are shown in Table 1. Data shown in table 1 arefrom the day 5 post-infestation recording. Little or no activity wasobserved in the E. coli negative control. Results indicate that theVip3B toxin has a broader spectrum of activity than the Vip3A toxinsince Vip3B was active against Ostrinia nubilalis and Plutellaxylostella. Results also suggest that Vip3B has a higher specificactivity to Helicoverpa zea than the Vip3A toxin.

TABLE 1 Percent Activity Mortality E. coli Spectrum of Insect pCIB9400pNOV1325 Control Vip3A^(b) Manduca sexta 100 100 0 + Agrotis ipsilon 100100 5 + Helicoverpa zea 100 100 10 + Heliothis virescens 100 100 10 +Spodoptera exguia 100 90 10 + Spodoptera frugiperda 100 100 0 + Ostrinianubilalis 100 100 0 − Plutella xylostella 100 100 0 − Trichplusia ni 100100 0 + Pectinophora 50^(a) 50^(a) 0 + gossypiella Cochyles hospes60^(a) 80^(a) 0 + ^(a)Surviving insects were observed to have severefeeding and growth inhibition. ^(b)A “+” indicates an insect speciesthat is susceptible to Vip3A. A ”−” indicates an insect species withlittle or no susceptibility of Vip3A.

Example 6 Construction of Maize Optimized vip3B Coding Sequence

A synthetic maize-optimized vip3B coding sequence was made according tothe procedure disclosed in U.S. Pat. No. 5,625,136. In this procedure,maize preferred codons, i.e., the single codon that most frequentlyencodes that amino acid in maize, are used. The maize preferred codonfor a particular amino acid is derived from known gene sequences frommaize. Maize codon usage for 28 genes from maize plants is found inMurray et al., Nucleic Acids Research 17:477-498 (1989). The syntheticvip3B coding sequence (SEQ ID NO: 3) was cloned into a pET101/D-Topoexpression vector. The resulting vector, designated pNOV1328, wastransformed into E. coli DH5α cells and deposited as ATCC accessionnumber PTA-3869.

Example 7 Creation of Transgenic Maize Plants Comprising a vip3B Gene

The synthetic maize-optimized vip3B (SEQ ID NO: 3) coding sequence waschosen for transformation into maize plants. An expression cassettecomprising the synthetic vip3B coding sequence was transferred to asuitable vector for Agrobacterium-mediated maize transformation. Threevectors were constructed for this example: (a) a vector comprising twovip3B expression cassettes, the first expression cassette comprisingMTL:vip3B, and the second expression cassette comprising PEPC:vip3B, (b)a vector comprising CMP:vip3B, and (c) a vector comprising UbiP:vip3B.All vectors used in this example also comprise the phosphomannoseisomerase (PMI) gene for selection of transgenic lines (Negrotto et al.(2000) Plant Cell Reports 19: 798-803).

All three vectors were individually transformed into maize.Transformation of immature maize embryos was performed essentially asdescribed in Negrotto et al., 2000, Plant Cell Reports 19: 798-803. Forthis example, all media constituents were as described in Negrotto etal., supra. However, various media constituents known in the art may besubstituted.

Agrobacterium strain LBA4404 (pSB1) containing the plant transformationplasmid was grown on YEP (yeast extract (5 g/L), peptone (10 g/L), NaCl(5 g/L), 15 g/l agar, pH 6.8) solid medium for 2-4 days at 28° C.Approximately 0.8×10⁹ Agrobacterium were suspended in LS-inf mediasupplemented with 100 μM As (Negrotto et al.,(2000) Plant Cell Rep 19:798-803). Bacteria were pre-induced in this medium for 30-60 minutes.

Immature embryos from A188 were excised from 8-12 day old ears intoliquid LS-inf+100 μM As. Immature embryos form other maize germplasm canalso be used. Embryos were rinsed once with fresh infection medium.Agrobacterium solution was then added and embryos were vortexed for 30seconds and allowed to settle with the bacteria for 5 minutes. Theembryos were then transferred scutellum side up to LSAs medium andcultured in the dark for two to three days. Subsequently, between 20 and25 embryos per petri plate were transferred to LSDc medium supplementedwith cefotaxime (250 mg/l) and silver nitrate (1.6 mg/l) and cultured inthe dark for 28° C. for approximately 10 days.

Immature embryos, producing embryogenic callus were transferred toLSD1M0.5S medium. The cultures were selected on this medium forapproximately 6 weeks with a subculture step at approximately 3 weeks.Surviving calli were transferred to Reg1 medium supplemented withmannose. Following culturing in the light (16 hour light/8 hour darkregiment), green tissues were then transferred to Reg2 medium withoutgrowth regulators and incubated for approximately 1-2 weeks. Plantletswere transferred to Magenta GA-7 boxes (Magenta Corp, Chicago Ill.)containing Reg3 medium and grown in the light. After approximately 2-3weeks, plants were tested for the presence of the PMI gene and the vip3Bgene by PCR. Positive plants from the PCR assay were transferred to thegreenhouse and tested for resistance to lepidopteran pests.

Example 8 Analysis of Transgenic Maize Plants Expressing Vip3B

Insect Bioassays

Plants were sampled as they were being transplanted from Magenta GA-7boxes into soil. Sampling consisted of cutting two small pieces of leaf(ca. 2-4 cm long) and placing each piece in a small petri dish. Negativecontrols were either transgenic plants that were PCR negative for thevip3B gene from the same transformation experiment, or fromnon-transgenic plants (of a similar size to test plants) that were beinggrown under similar growth conditions as the transgenics.

Leaf samples from each plant were inoculated with either European cornborer (Ostrinia nubilalis) or fall armyworm (Spodoptera frugiperda) byplacing 10 first instar larvae onto each leaf piece. Petri dishes arethen tightly sealed. Other suitable insect pests can also be used.

At approximately 3-4 days post inoculation, data was collected. Thepercent mortality of the larvae was calculated. Also, a visual damagerating of the leaf can be ascertained at the same time. Feeding damageis rated as high, moderate, low, or absent and given a numerical valueof 3, 2, 1 or 0, respectively.

Results of the bioassay of the transgenic plants are shown in Table 2.Results indicate that transgenic maize plants comprising the vip3B geneand expressing the Vip3B protein, are insecticidal to European cornborer and fall armyworm.

TABLE 2 Efficacy of Trangenic Maize Plants Expressing Vip3B.Promter:vip3B Event Construct % FAW Mortality Per Plant^(a) % ECBMortality Per Plant^(b) 118A MTL:vip3B/ 100, 100, 100, 100, 100, 90,100, 100, 90, 100, PEPC:vip3B 100, 100, 100, 100, 100, 100, 80, 100 100,100, 100, 100, 100, 100, 100, 100, 90, 90, 90, 100, 100, 100, 100, 100,100, 100 90, 100, 70, 80, 100, 100, 100, 100, 100, 70, 100, 100, 100,70, 100, 100, 100 100, 80, 80 121A MTL:vip3B/ 90, 100, 100, 100, 100,70, 80, 70, 90, 80, 80, PEPC:vip3B 100, 100, 100, 100, 100, 90, 80, 80,90, 100, 100, 100, 100, 100, 100, 100, 80, 90, 70, 90, 100, 100, 100,100, 100, 80, 100, 80, 100, 70, 100, 100, 100, 100, 100, 80, 70, 70, 90,100, 100, 100, 100, 100, 100, 100, 90 90, 90, 90 100 142C MTL:vip3B/100, 100, 100, 100, 100, 80, 100, 90, 80, 90, PEPC:vip3B 100, 100, 100,100 70, 70, 90, 90 145B MTL:vip3B/ 100, 100, 100, 100, 100, 80, 70, 90,100, 70, PEPC:vip3B 100, 100, 100, 100, 100, 70, 100, 80, 80, 70, 100,100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100 70, 100, 90,90, 90  89A CMP:vip3B 100, 100, 100, 100, 100, 100, 100, 100, 100, 100,100, 100 100, 100, 100, 100 190A CMP:vip3B 100, 100, 100, 100, 100, 100,80, 90, 80, 90, 100, 100, 100, 100 100, 80, 100, 80 ^(a)FAW = fallarmyworm ^(b)ECB = European corn borerELISA Assay

Levels of Vip3B protein in various transgenic maize tissues weredetermined using an ELISA. ELISA analysis was done according to themethod disclosed in U.S. Pat. No. 5,625,136. Results of the ELISAanalysis are shown in Table 3.

TABLE 3 Vip3B Protein Levels in Transgenic Maize. Mean Vip3B ProteinLevel in Specified Tissue (μg/mg soluble protein) Event Leaf Pith RindPollen 118A 20 ± 12 .316 ± .240 .686 ± .645 0 121A 20 ± 19 .523 ± .387.723 ± .343 0 142C 18 ± 17 1.12 ± .770 3.75 ± 1.30 0 145B 19 ± 13 .720 ±.720 2.23 ± 2.0  0

Example 9 Hybrid Vip3 Toxins

Vip3B is toxic to Ostrinia nubilalis (European corn borer) and Plutellaxylostella (diamond back moth), whereas a related Vip toxin, Vip3A, haslittle or no activity. Vip3B and Vip3A differ primarily in theC-terminal region of their respective amino acid sequences particularlyin the region from amino acid 579 to amino acid 787 of SEQ ID NO: 2. Inorder to demonstrate that this C-terminal region of Vip3B is the portionof the Vip3B toxin that is sufficient for the activity against Europeancorn borer and diamond back moth, a hybrid toxin comprising theC-terminal region of Vip3B, starting at amino acid number 579 and endingat amino acid number 787 of SEQ ID NO: 2, was joined in an amino tocarboxy direction with the N-terminal region of Vip3A, starting at aminoacid number 1 and ending at amino acid number 578 of SEQ ID NO: 5. Thehybrid toxin was designated Vip3A-B (SEQ ID NO: 7).

The nucleic acid molecule encoding the Vip3A-B hybrid toxin wasconstructed using two steps of PCR with the following primers:

VIP3A-N: 5′-ATGACCAAGAATAATACTAAATTAAGCAC-3′ (SEQ ID NO: 10) VIPfus4:5′-TCCTTATGAACATATAAAGCTTTAGTTCCATT-3′ (SEQ ID NO: 11) VIP3B-C:5′-GGCGAATTCTCACTTAATCGAAAAATTCCGGAAATTTAT-3′ (SEQ ID NO: 12) VIPfus3:5′-AATGGAACTAAAGCTTTATATGTTCATAAGGA-3′ (SEQ ID NO: 13)

In the first PCR step, primers Vip3A-N (SEQ ID NO: 10) and Vipfus4 (SEQID NO: 11) were used to generate an approximately 1.7 kb fragment of the5′ end of the vip3A gene, encoding the N-terminal region, and primersVip3B-C (SEQ ID NO: 12) and Vipfus3 (SEQ ID NO: 13) were used togenerate an approximately 0.7 kb fragment of the 3′ end of the vip3Bgene encoding the C-terminal region. In the second PCR step, these twofragments were combined as the templates for primers Vip3A-N (SEQ ID NO:10) and Vip3B-C (SEQ ID NO: 12) to generate an approximately 2.4 kbhybrid vip3A-vip3B gene, designated vip3A-B (SEQ ID NO: 6).

An E. coli clone expressing the hybrid Vip3A-B toxin was tested forinsecticidal activity against fall armyworm and European corn borerusing the method outlined in Example 5. Results of some of the bioassayssuggested that the C-terminal region of Vip3B is sufficient to conferEuropean corn borer activity on the hybrid toxin.

Example 10 In Vitro Recombination of vip3 Genes by DNA Shuffling

One of the vip3 genes of the present invention, for example SEQ ID NO:1, 3, or 6 is amplified by PCR. The resulting DNA fragment is digestedby DNaseI treatment essentially as described in Stemmer et al, PNAS 91:10747-10751 (1994), and the PCR primers are removed from the reactionmixture. A PCR reaction is carried out without primers and is followedby a PCR reaction with the primers, both as described in Stemmer et al.(1994). The resulting DNA fragments are cloned into pTRC99a (Pharmacia,Cat no: 27-5007-01) and transformed into E. coli strain SASX38 byelectroporation using the Biorad Gene Pulser and the manufacturer'sconditions. The transformed bacteria are grown on medium overnight andscreened for insecticidal activity.

In a similar reaction, PCR-amplified DNA fragments comprising one of thevip3 genes described herein (SEQ ID NO: 1, 3, or 6, or mutants thereof),and PCR-amplified DNA fragments comprising at least one other of thevip3 genes described herein (or a mutant thereof) are recombined invitro and resulting variants with improved insecticidal properties arerecovered as described below.

In order to increase the diversity of the shuffled vip3 gene library, avip3 gene or genes (called the primary genes) are shuffled usingsynthetic oligonucleotide shuffling. A plurality (e.g., 2, 5, 10, 20,50, 75, or 100 or more) of oligonucleotides corresponding to at leastone region of diversity are synthesized. These oligonucleotides can beshuffled directly, or can be recombined with one or more of the familyof nucleic acids.

The oligonucleotide sequence can be taken from other vip3 genes calledsecondary genes. The secondary genes have a certain degree of homologyto the primary genes. There are several ways to select parts of thesecondary gene for the oligonucleotide synthesis. For example, portionsof the secondary gene can be selected at random. The DNA shufflingprocess will select those oligonucleotides, which can be incorporatedinto the shuffled genes.

The selected portions can be any lengths as long as they are suitable tosynthesize. The oligonucleotides can also be designed based on thehomology between the primary and secondary genes. A certain degree ofhomology is necessary for crossover, which must occur among DNAfragments during the shuffling. At the same time, strong heterogeneityis desired for the diversity of the shuffled gene library. Furthermore,a specific portion of the secondary genes can be selected for theoligonucleotide synthesis based on the knowledge in the protein sequenceand function relationship.

The present invention has disclosed that the C-terminal domain of Vip3Bis in part responsible for spectrum of activity of the Vip3 toxins. Whenthe insecticidal spectrum is modified by the current invention utilizingthe DNA shuffling technology, the C-terminal region of the nucleotidesequence of the secondary genes can be selected as a target region forsynthesizing oligonucleotides used in an oligonucleotide shufflingprocedure.

Since the insecticidal activity of the Vip3 protein is dependent, atleast in part, to the N-terminal region, the N-terminal region of thesecondary genes can be selected for oligonucleotide shuffling forincreased insecticidal activity.

Example 11 High-throughput Screen for Insecticidal Activity

Shuffled vip3 gene libraries in either E. coli or Bacillus thuringiensisare screened for insecticidal activity. Colonies are picked with a Q-bot(Beckman), placed in growth media in a standard 96-well format and grownover night. Each clone is then layered onto the surface of an insectdiet in 96-well format and the surface allowed to dry. Optionally, poolsof transformed cells are added to each well to increase the number ofclones that are tested in the initial screening round. For example,screening 100 clones per well and using 10,000 wells provides a screenof 10⁶ clones.

Several neonate larvae of a target insect, for example, Heliothisvirescens, Helicoverpa zea or Spodoptera frugiperda, are added to eachwell. The plate is covered with an air permeable membrane that retainsthe larvae in the wells into which they were placed. After 5 days thewells are evaluated for amount of diet consumed and/or insect mortality.Clones in wells indicating that little or no diet is consumed and/orwhere high insect mortality is observed are chosen for further analysis.Several clones should be found to have enhanced activity against thetarget insect.

All publications and patent applications mentioned in this specificationare indicative of the level of skill of those skilled in the art thatthis invention pertains. All publications and patent applications areherein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

It should be understood that the examples and embodiments describedherein are for illustrative purposes only and that various modificationsor changes in light thereof will be suggested to persons skilled in theart and are to be included within the spirit and purview of thisapplication and the scope of the appended claims.

1. An isolated toxin that is active against European corn borer, whereinsaid toxin comprises an amino acid sequence that has at least 93%sequence identity with the amino acid sequence set forth in SEQ ID NO: 2over the full length of the amino acid sequence and wherein theC-terminus of said toxin comprises amino acids 579-787 of SEQ ID NO: 2.2. The isolated toxin according to claim 1, wherein said toxin comprisesthe amino acid sequence set forth in SEQ ID NO:
 2. 3. The isolated toxinaccording to claim 1, wherein said toxin is produced by the expressionof a nucleic acid molecule comprising the nucleotide sequence set forthin SEQ ID NO: 1 or SEQ ID NO:
 6. 4. The isolated toxin according claim1, wherein said toxin is produced by the expression of a nucleotidesequence comprising the approximately 2.4 kb DNA fragment comprised inpNOV1325 (ATCC PTA-3868).
 5. The isolated toxin according to claim 1,wherein said toxin is produced by the expression of a nucleotidesequence comprising the approximately 2.4 kb DNA fragment comprised inpNOV1328 (ATCC PTA-3869).
 6. The isolated toxin according to claim 1,wherein said toxin is active against at least one additionallepidopteran insect.
 7. The isolated toxin according to claim 6, whereinsaid lepidopteran insect is selected from the group consisting ofPlutella xylostella (diamondback moth), Spodoptera frugiperda (fallarmyworm), Agrotis ipsilon (black cutworm), Helicoverpa zea (cornearworm), Heliothis virescens (tobacco budworm), Spodoptera exigua (beetarmyworm), Helicoverpa punctigera (native budworm), Helicoverpa armigera(cotton bollworm), Manduca sexta (tobacco hornworm), Trichoplusia ni(cabbage looper), Pectinophora gossypiella (pink bollworm), and Cochylishospes (banded sunflower moth).
 8. A composition comprising an effectiveinsect-controlling amount of the toxin according to claim
 1. 9. Anisolated toxin active against European corn borer produced by the methodcomprising: (a) transforming a host cell with a nucleic acid moleculecomprising a promoter operably linked to a nucleotide sequence encodingthe toxin of claim 1; (b) growing the host cell under conditions whichallow expression of the toxin; and (b) recovering said toxin.